Biblatex: add "submitted to" or "to appear in" for some publications

Question

Some of my articles are accepted for publication, others are not. In my bibliography I have to state the not yet accepted ones as "Submitted to" and accepted but not published ones as "To appear in". In addition, references for conference papers should include "Paper submitted to". I have added a description of the three different cases illustrating the problem both in connection to a list have made with \fullcite and the bibliography.

%CLASS and GEOMETRY and PDFs
\documentclass{report}
\usepackage[
    a4paper,
    bindingoffset=0.5cm, left=2.6cm,right=2.6cm,top=2.6cm,bottom=3cm, 
    footskip=.67cm]
    {geometry}
\usepackage{pdfpages}

%FONT and language
\usepackage{gensymb}
\usepackage{polyglossia}
\setdefaultlanguage{english}
\usepackage{xeCJK}
\usepackage{ruby}
\renewcommand{\rubysize}{0.5} % default: 0.4
\renewcommand{\rubysep}{-0.3ex}
\setCJKmainfont{TakaoMincho}

%FLOATS - table and graphics
\usepackage{float}
\usepackage{array} 
\usepackage{longtable}
\setlength\tabcolsep{2mm}
\usepackage{enumitem}
\setlist{noitemsep}

% TOC og LOFT mellemrum
\usepackage{tocloft}
\setlength{\cftbeforesecskip}{2mm} 
\setlength{\cftbeforefigskip}{2mm} 
\setlength{\cftbeforetabskip}{2mm}
\setcounter{secnumdepth}{-3}

%GRAPHICS
\usepackage{graphicx}
\usepackage{tcolorbox}

%SHORT CUTS
\newcommand{\sub}[1]{\textsubscript{#1}}
\newcommand{\ul}[1]{\underline{#1}}
\newcommand{\arrl}{\textleftarrow}
\newcommand{\arrr}{\textrightarrow}
\newcommand{\arrlr}{\textleftrightarrow}

\newcommand{\prs}[1]{PrS\sub{#1}}
\newcommand{\pos}[1]{PoS\sub{#1}}
\newcommand{\obs}[1]{ObS\sub{#1}}
\newcommand{\ds}[1]{DS\sub{#1}}

%BIBLIOGRAPHY
\usepackage[
    backend=biber,
    sortlocale=danish,
    firstinits=true,
    style=authoryear-icomp,
    dashed=false,
    doi=false,
    isbn=false,
    url=true,]
    {biblatex}
\DeclareNameAlias{sortname}{family-given}
\renewbibmacro{in:}{%
    \ifboolexpr{%
        test {\ifentrytype{article}}%
        or
        test {\ifentrytype{inproceedings}}%
    }{}{\printtext{\bibstring{in}\intitlepunct}}%
    }
\makeatletter
\newcommand{\tempmaxup}[1]{\def\blx@maxcitenames{99}#1}
\makeatother
\DeclareCiteCommand{\fullcite}[\tempmaxup] %sets name order to last-first 
    {\usebibmacro{prenote}}
    {\usedriver
        {\DeclareNameAlias{sortname}{default}}
        {\thefield{entrytype}}}
    {\multicitedelim}
    {\usebibmacro{postnote}}

\addbibresource{\jobname.bib}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
    @incollection{winslow2018,
        title = {Theorizing {{Lesson Study}}: {{Two}} Related Frameworks and Two {{Danish}} Case-Studies},
        booktitle = {({{To}} Appear) {{Mathematics Lesson Study Around}} the {{World}}: {{Theoretical}} and Methodological Issues},
        series = {Springer book series of ICME},
        publisher = {{Springer}},
        date = {2018},
        author = {Winsløw, Carl and Bahn, Jacob and Rasmussen, Klaus},
        editor = {Quaresma, Marisa and Winsløw, Carl and Clivaz, Stéphane and da Ponte, João and Ní Shúilleabháin, Aoibhinn and Takahashi, Akihiko},

    }
    @article{bahn2017c,
        title = {Evolution of Teachers' Anticipation of Didactical Situations in the Course of Three Lesson Studies},
        journaltitle = {(article submitted for) Annales de didactique et de Sciences Cognitives},
        date = {2017},
        author = {Bahn, Jacob},

    }

    @inproceedings{bahn2017d,
        location = {{Nagoya, Japan}},
        title = {How Infrastructures of Lesson Studies Impact on Teachers' Learning},
        eventtitle = {(Paper Submitted to) {{WALS Conference}} 2017},
        year = {2017/11/24-26},
        author = {Bahn, Jacob},

    }
\end{filecontents}

%TITLE and AUTHOR and FRONTPAGE
\usepackage{authblk}
\usepackage{eso-pic}

%FONT 
\setmainfont{Liberation Serif}

\begin{document}
\chapter{List of all papers and abstracts produced }
\noindent \fullcite{bahn2017c}.
\bigskip \noindent \fullcite{bahn2017d}.
\bigskip \noindent \fullcite{winslow2018}.
\section{References} % REFERENCES  ---------------------------------
\sloppy
\printbibliography[heading=none]
\end{document}

Answer 1

The straightforward solution is an extension of lockstep's answer to Localize terms in bibtex/biblatex entries

\documentclass{article}
\usepackage[style=authoryear]{biblatex}
\addbibresource{biblatex-examples.bib}

\usepackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@incollection{A01,
  author = {Author, A.},
  booktitle = {Foo},
  editor = {Emma Ditor},
  year = {2001},
  title = {Alpha},
  pubstate = {toappear},
}
\end{filecontents*}
\addbibresource{\jobname.bib}

\NewBibliographyString{toappear}
\DefineBibliographyStrings{english}{%
  toappear = {to appear},
}

\renewbibmacro*{in:}{%
  \iffieldundef{pubstate}
    {}
    {\printfield{pubstate}%
     \setunit{\addspace}%
     \clearfield{pubstate}}%
  \printtext{%
    \bibstring{in}\intitlepunct}}

\begin{document}
\cite{A01,westfahl:space}
\printbibliography
\end{document}

---

A more involved solution that handles different prepositions would be

\NewBibliographyString{toappearin}
\NewBibliographyString{submittedto}
\DefineBibliographyStrings{english}{%
  toappearin  = {to appear in},
  submittedto = {submitted to},
}

\renewbibmacro*{in:}{%
  \ifboolexpr{not test {\iffieldundef{pubstate}}
              and (test {\iffieldequalstr{pubstate}{toappearin}}
                   or test{\iffieldequalstr{pubstate}{submittedto}})}
    {\printtext{%
       \printfield{pubstate}\intitlepunct}%
     \clearfield{pubstate}}
    {\printtext{%
       \bibstring{in}\intitlepunct}}}

In addition: This solution works perfect in combination with the export trick revealed here: https://github.com/retorquere/zotero-better-bibtex/wiki/Customized-Exports