Citing two authors/Journals: Issue(Number)

Question

A while back, this customized Bib-style has been craftet for me on this platform and it has been working great ever since. Now, I have to change it up a little bit but don't know how: Whenever I'm citing a book/article that's been written by two people, the initial of the second author's first name shows up. This hasn't been a problem, but now I've been told that I should get rid of it... I know what the different parts of the code do, but I don't think just deleting a part of the code will do the trick (it hasn't yet for me at least) so I need your help! Thank you so much in advance!

Edit: I have added my entire (messy...) preamble because I seem to have lost the overview over everything... I'll have to sort this out soonish. Also I have added two 'problematic' Bib entries: knobel2007a produces "Knobel/C. ( Lankshear (2007)" instead of the desired "Knobel/Lankshear (2007)" (I know that the basic problem lies in the fact that I have manually added (eds.) after their names, but this makes other entries shorter). The other one in berg2012a that produces in the bibliography "In: Written Language and Literacy 15.1" when I want it to be "In: Written Language and Literacy 15(1)" (The journal title itself should remain cursive while the rest is upright).

If there is still information missing, please let me know and thank you for your time you've already spent helping me!

\documentclass[paper=a4,12pt,numbers=endperiod]{scrartcl}
\usepackage{pgfplots}
\usepackage{xltxtra}

\usepackage[left=2cm,right=3cm,top=2cm,bottom=2cm,footskip=1cm]{geometry}
\usepackage{scrlayer-scrpage}

%\usepackage{fontspec}
\setmainfont[SmallCapsFont={* Caps}]{Latin Modern Roman}
\setsansfont{Latin Modern Sans}
\setmonofont{Old Standard}
\newfontfamily\russianfont{Old Standard}
\newfontfamily\ipafont{Doulos SIL}
\newfontfamily\churchslavonicfont{Ponomar Unicode}

\usepackage{polyglossia}
\usepackage{churchslavonic}
\setdefaultlanguage{english}
%\setotherlanguages{german,romanian,russian,churchslavonic}
\usepackage[autostyle=true]{csquotes}

\usepackage{yfonts}
%\usepackage{tipa}
%\usepackage{ifxetex}
%\usepackage{combelow}
\usepackage{hanging}
\setlength\columnsep{20pt}

\usepackage{setspace}
\usepackage{filecontents}

\usepackage{graphicx}
\usepackage{float}
\usepackage{caption}

\usepackage[english]{fancyref}
\renewcommand{\fancyrefdefaultformat}{plain}
\renewcommand{\fancyrefdefaultspacing}{\fancyreftightspacing}
\newcommand*{\fancyrefapplabelprefix}{app}
\newcommand*{\appendname}{appendix}
\frefformat{plain}{\fancyrefapplabelprefix}{\appendname\fancyrefdefaultspacing#1}
\renewcommand*{\fancyrefseclabelprefix}{sec}
\newcommand*{\sectionname}{section}
\frefformat{plain}{\fancyrefseclabelprefix}{\sectionname\fancyrefdefaultspacing#1.}
\newcommand*{\fancyrefsublabelprefix}{sub}
\newcommand*{\subsectionname}{subsection}
\frefformat{plain}{\fancyrefsublabelprefix}{\subsectionname\fancyrefdefaultspacing#1.}
\renewcommand*{\fancyreftablabelprefix}{tab}
\renewcommand*{\tablename}{table}
\frefformat{plain}{\fancyreftablabelprefix}{\tablename\fancyrefdefaultspacing#1.}

\usepackage{multicol}

\usepackage{scrextend}
\addtokomafont{labelinglabel}{\sffamily}

%%Tables%%
\usepackage{array}
\usepackage{booktabs}
\usepackage{tabularx}
\usepackage[table]{colortbl}
\usepackage{multirow}
\usepackage{diagbox}

\usepackage{lipsum}

\usepackage{pdfpages}
\usepackage{hyperref}
\usepackage{url}

\usepackage[footnote,printonlyused]{acronym}
\usepackage{footnote}
\makesavenoteenv{tabular}
\makesavenoteenv{table}
\deffootnote[1.0em]{1.0em}{1.0em}
    {\textsuperscript{\thefootnotemark}\,\enskip}

\setkomafont{disposition}{\mdseries\rmfamily}
\onehalfspacing
\renewcommand{\baselinestretch}{1.5}

%%ToC%%
\KOMAoptions{
    toc=sectionentrydotfill,
    listof=totoc
}

\newkomafont{standardsection}{\Large}
\newkomafont{nsection}{\usekomafont{standardsection}\slshape}

\DeclareTOCStyleEntry[%
level=\sectiontocdepth,%
beforeskip=0pt plus .2pt,%
indent=0pt,%
numwidth=1.5em,%
entryformat=\usekomafont{sectionentry}\textsl%
]{section}{nsection}

\newcommand*\usensection{% define switch to nsection
    \addtocontents{toc}{\protect\addvspace{1em plus 1pt}}% additional space in TOC before the first nsection entry
    \setkomafont{section}{\usekomafont{nsection}}%
    \renewcommand\addsectiontocentry[2]{\addtocentrydefault{nsection}{##1}{##2}}%
}
\newcommand*\usestandardsection{% define switch to standard section
    \setkomafont{section}{\usekomafont{standardsection}}%
    \renewcommand\addsectiontocentry[2]{\addtocentrydefault{section}{##1}{##2}}%
}

\AfterTOCHead[toc]{\thispagestyle{empty}\pagestyle{empty}}
\AfterStartingTOC[toc]{\clearpage}

%%Bibliography%%
\usepackage[nottoc,notlot,notlof]{tocbibind}
\usepackage[backend=biber,style=authoryear]{biblatex}
\addbibresource{TransAlph.bib}
\DefineBibliographyStrings{english}{references={Bibliography}}

\DeclareFieldFormat{editortype}{\mkbibparens{#1}}
\renewbibmacro*{byeditor+others}{%
    \ifnameundef{editor}
    {}
    {\printnames[byeditor]{editor}%
        \setunit{\addspace}%
        \usebibmacro{byeditor+othersstrg}%
        \clearname{editor}%
        \newunit}%
    \usebibmacro{byeditorx}%
    \usebibmacro{bytranslator+others}}
\renewbibmacro*{byeditor+othersstrg}{\usebibmacro{editor+othersstrg}}
\renewbibmacro*{bytranslator+othersstrg}{\usebibmacro{translator+othersstrg}}
\renewbibmacro*{bytypestrg}[2]{%
    \iffieldundef{#1type}
    {\bibstring{#2}}
    {\ifbibxstring{\thefield{#1type}}
        {\bibstring{\thefield{#1type}}}
        {\printtext{\thefield{#1type}}}}}

\renewcommand*{\multinamedelim}{/}
\renewcommand*{\finalnamedelim}{\multinamedelim}

\renewcommand*{\labelnamepunct}{\addcolon\space}
\renewcommand*{\postnotedelim}{\addcolon\space}
\DeclareFieldFormat{postnote}{#1}
\DeclareFieldFormat{multipostnote}{#1}

\DeclareFieldFormat{superedition}{\textsuperscript{#1}}

\providecommand*{\iflabeldateisdate}{%
    \ifboolexpr{%
        not test {\iffieldundef{labeldatesource}}
        and 
        (test {\iffieldequalstr{labeldatesource}{}} 
        or test {\iffieldequalstr{labeldatesource}{year}})}}

\renewbibmacro*{date+extrayear}{%
    \iffieldundef{labelyear}
    {}
    {\usebibmacro{origdate}%
        \setunit*{\addspace}%
        \printtext[parens]{%
            \iflabeldateisdate
            {\iffieldnum{edition}
                {\printfield[superedition]{edition}%
                    \global\clearfield{edition}}
                {}%
                \printdateextra}
            {\printlabeldateextra}}}}

\newbibmacro*{origdate}{%
    \iffieldundef{origyear}
    {}
    {\printtext[brackets]{\printorigdate}}}

\renewcommand*{\bibpagespunct}{\addcolon\space}
\DeclareFieldFormat{pages}{#1}

\DeclareNameAlias{sortname}{family-given}

\renewcommand*{\labelnamepunct}{\addcolon\space}
\newcounter{SprachB}
\newcommand{\SprachB}[1]{\refstepcounter{SprachB}\label{#1}}

\usepackage{etoolbox}
\AtBeginEnvironment{quote}{\singlespacing\footnotesize}

\newcommand{\graphem}[1]{\guilsinglleft {#1}\guilsinglright}
\newcommand{\ipa}[1]{{\ipafont {#1}}}
\newcommand{\aks}[1]{{\churchslavonicfont {#1}}}
\newcommand{\rus}[1]{{\russianfont {#1}}}
\newcommand{\phonem}[1]{/\ipa{#1}/}
\newcommand{\phon}[1]{[\ipa{#1}]}

\newcommand{\sog}[1]{‘{#1}’}
\newcommand{\zit}[1]{“{#1}”}

\hyphenation{Script-Ora-lia}

\usepackage{silence}

\pagestyle{scrheadings}
\cfoot{}
\ofoot{\pagemark\hspace{-.5cm}}

\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
@Book{knobel2007a,
Title                    = {A New Literacies Sampler \textup{(New Literacies and Digital Epistemologies\,29)}},
Author                   = {Knobel, Michele and Lankshear, Colin (eds.)},
Keywords                 = {sek},
Location                 = {New\,York},
Publisher                = {Peter Lang},
Year                     = {2007}
}
@Article{berg2012a,
Title                    = {Identifying Graphematic Units. Vowel and Consonant Letters},
Author                   = {Berg, Kristian},
Journal                  = {Written Language \& Literacy},
Keywords                 = {sek},
Number                   = {1},
Pages                    = {26--45},
Volume                   = {15},
Year                     = {2012}
}
\end{filecontents}

\begin{document}
Example sentence \textcite[cf.][3--6]{knobel2007a}.\\
Another example sentence \parencite[][39]{berg2012a}.
\bibliography{\jobname}
\end{document}

Answer 1

After removing the unnecessary stuff and making the code compilable, the output for me is

so I can not reproduce the weird name issue.

But still

author = {Knobel, Michele and Lankshear, Colin (eds.)},

in knobel2007a is wrong. If the two are editors they should be marked as such properly with

editor = {Knobel, Michele and Lankshear, Colin},

Biber/BibTeX can get confused parsing the name with the appended (eds.) and produce weird output because of that. What you are seeing could be explained if you have a second source authored or edited by Colin Lankshear (or any other Lankshear for that matter). In that case the uniquename feature would try to distinguish Lankshear, Colin and Lanksehar, Colin (eds.) thinking that the two are different people, so it adds the name initial, because Lanksehar, Colin (eds.) is not quite the best input, Biber thinks the initials are "C. (. Lankshear" and prints that. Name disambihuation can be turned off as explained in biblatex, authoryear style: In-text citations display first name initials for certain bibliography entries and Literature with Biber generates strange citations: firstnames appear erratically.

It also seems to me as though knobel2007a is actually a @collection and not a @book. A @book is normally a work that was written in its entirety by the same set of authors, while a @collection is a, well ... collection of contributions by different authors curated by editors.

For the volume(number) thing you only need to redefine the bibmacro volume+number+eid and change the field format for number. See the MWE below.

I have slightly modernised your code for biblatex 3.11 and so with

\documentclass[paper=a4,12pt,numbers=endperiod]{scrartcl}

\usepackage[backend=biber,style=authoryear]{biblatex}
\DefineBibliographyStrings{english}{references={Bibliography}}

\DeclareFieldFormat{editortype}{\mkbibparens{#1}}
\DeclareDelimFormat{editortypedelim}{\addspace}
\renewbibmacro*{byeditor+others}{%
  \ifnameundef{editor}
    {}
    {\printnames[byeditor]{editor}%
     \setunit{\addspace}%
     \usebibmacro{byeditor+othersstrg}%
     \clearname{editor}%
     \newunit}%
  \usebibmacro{byeditorx}%
  \usebibmacro{bytranslator+others}}
\renewbibmacro*{byeditor+othersstrg}{\usebibmacro{editor+othersstrg}}
\renewbibmacro*{bytranslator+othersstrg}{\usebibmacro{translator+othersstrg}}
\renewbibmacro*{bytypestrg}[2]{%
  \iffieldundef{#1type}
    {\bibstring{#2}}
    {\ifbibxstring{\thefield{#1type}}
       {\bibstring{\thefield{#1type}}}
       {\printtext{\thefield{#1type}}}}}

\DeclareDelimFormat{multinamedelim}{\addslash}
\DeclareDelimAlias{finalnamedelim}{multinamedelim}

\DeclareDelimFormat[bib]{nametitledelim}{\addcolon\space}

\renewcommand*{\postnotedelim}{\addcolon\space}
\DeclareFieldFormat{postnote}{#1}
\DeclareFieldFormat{multipostnote}{#1}

\DeclareFieldFormat{superedition}{\textsuperscript{#1}}

\renewbibmacro*{date+extradate}{%
  \iffieldundef{labelyear}
    {}
    {\usebibmacro{origdate}%
     \setunit*{\addspace}%
     \printtext[parens]{%
       \iflabeldateisdate
         {\iffieldnum{edition}
            {\printfield[superedition]{edition}%
             \global\clearfield{edition}}
            {}%
          \printdateextra}
         {\printlabeldateextra}}}}

\newbibmacro*{origdate}{%
  \iffieldundef{origyear}
    {}
    {\printtext[brackets]{\printorigdate}}}

\renewcommand*{\bibpagespunct}{\addcolon\space}
\DeclareFieldFormat{pages}{#1}

\DeclareNameAlias{sortname}{family-given}

\DeclareFieldFormat[article,periodical]{number}{\mkbibparens{#1}}
\renewbibmacro*{volume+number+eid}{%
  \printfield{volume}%
  %\setunit*{\adddot}%<- comment this
  \printfield{number}%
  \setunit{\addcomma\space}%
  \printfield{eid}}

\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@collection{knobel2007a,
  title     = {A New Literacies Sampler},
  editor    = {Knobel, Michele and Lankshear, Colin},
  keywords  = {sek},
  location  = {New York},
  publisher = {Peter Lang},
  year      = {2007},
  series    = {New Literacies and Digital Epistemologies},
  number    = {29},
}
@article{berg2012a,
  title    = {Identifying Graphematic Units. Vowel and Consonant Letters},
  author   = {Berg, Kristian},
  journal  = {Written Language \& Literacy},
  keywords = {sek},
  number   = {1},
  pages    = {26--45},
  volume   = {15},
  year     = {2012}
}
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
Example sentence \textcite[cf.][3--6]{knobel2007a}.
Another example sentence \parencite[][39]{berg2012a}.

\printbibliography
\end{document}

we obtain