Trying to reproduce entry fields for a multivolume book (best practice?)

Question

Translation of the red square is this:

Translation by Ionuț Bița
Edition, notes and commentaries by Nelu Zugravu

Here is the MWE:

\documentclass[a4paper]{article}
\usepackage[english]{babel}
\usepackage[backend=biber]{biblatex}
\begin{filecontents}{\jobname.bib}
@mvbook{berstein:ist:eur,
  maintitle    = {Istoria Europei},
  title        = {Moștenirea Antichității},
  author       = {Berstein, Serge and Milza, Pierre},
  year         = {1997},
  publisher    = {Institutul European},
  location     = {Iași},
  series       = {Sinteze},
  volume       = {1},
  isbn         = {973-586-027-9},
  volumes      = {5},
  translator   = {Bița, Ionuț},
  editor      = {Zugravu, Nelu},
  editortype  = {\bibstring{editor}, \bibstring{annotations} and \bibstring{bycommentator}},
  pagetotal    = {372}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
\nocite{*}
\printbibliography
\end{document}

I'm interested in particular if is used correctly editortype or is a different way to put that explanations without:

editor      = {Zugravu, Nelu},
annotator   = {Zugravu, Nelu},
commentator = {Zugravu, Nelu},

Answer 1

In principle I'd prefer the version with

editor       = {Zugravu, Nelu},
annotator    = {Zugravu, Nelu},
commentator  = {Zugravu, Nelu},

even though it looks a bit repetitive in the input.

The problem with that is that biblatex then chooses the order in which it puts these roles in the bibliography. This order may be different from the order on the title page of the work you are citing. Furthermore, while biblatex has some support for combined roles, not all possible combinations are supported out of the box, so you may find that some things get split up unexpectedly. (See also the discussion at the end of my answer to Is the order of fields in an entry in a .bib file important for printing the bibliography?) If either of that bothers you, you can indeed force a particular description with

editor      = {Zugravu, Nelu},
editortype  = {<exact discription here>},

editortype can either be the identifier of a bibstring (like editortype = {editor} or editortype = {editortrco},) or free-form text (which may or may not include \bibstring calls). The problem with giving a free-form text is that the text cannot be changed easily to work in different contexts. biblatex sometimes puts the role after the name (editor and friends)

Zugravu, Nelu (editor)

and sometimes before the name (byeditor and friends)

edited by Nelu Zugravu

a hard-coded editorstring might not work for both situations. That said, you can often be pretty sure as to how the info will appear in the bibliography (in our case, we can be very confident it's going to be before the name).

I probably wouldn't use

editortype = {\bibstring{editor}, \bibstring{annotations} and \bibstring{bycommentator}},

because it mixes the two types of bibstrings (before and after the name). You can see that this goes wrong if you load biblatex with the option abbreviate=false. Then we get

Editor, annotations and commented by Nelu Zugravu

which doesn't look right.

The usage of and together with \bibstring commands also looks odd, because the strings will be translated, but not the and. If I switch to German I get

Hrsg., Erläut. and komm. von Nelu Zugravu.

which has an untranslated "and" (should be "und" in German) and wrong capitalisation because it mixes the two types of strings.

So if you want to go down the editortype route, I'd suggest you either just hard-code the string you want to see (which then cannot be translated etc.) or you define a new bibliography string and use that

\documentclass[a4paper]{article}
\usepackage[english]{babel}
\usepackage[backend=biber]{biblatex}
\NewBibliographyString{byeditoranco}
\DefineBibliographyStrings{english}{
  byeditoranco = {edited, annotated\finalandcomma\ and commented by},
}
\begin{filecontents}{\jobname.bib}
@mvbook{berstein:ist:eur:hardcode,
  maintitle    = {Istoria Europei},
  title        = {Moștenirea Antichității},
  author       = {Berstein, Serge and Milza, Pierre},
  year         = {1996},
  publisher    = {Institutul European},
  location     = {Iași},
  series       = {Sinteze},
  volume       = {1},
  isbn         = {973-586-027-9},
  volumes      = {5},
  translator   = {Bița, Ionuț},
  editor       = {Zugravu, Nelu},
  editortype   = {\autocap{e}dited, annotated and commented by},
  pagetotal    = {372}
}
@mvbook{berstein:ist:eur:names,
  maintitle    = {Istoria Europei},
  title        = {Moștenirea Antichității},
  author       = {Berstein, Serge and Milza, Pierre},
  year         = {1997},
  publisher    = {Institutul European},
  location     = {Iași},
  series       = {Sinteze},
  volume       = {1},
  isbn         = {973-586-027-9},
  volumes      = {5},
  translator   = {Bița, Ionuț},
  editor       = {Zugravu, Nelu},
  annotator    = {Zugravu, Nelu},
  commentator  = {Zugravu, Nelu},
  pagetotal    = {372}
}
@mvbook{berstein:ist:eur:string,
  maintitle    = {Istoria Europei},
  title        = {Moștenirea Antichității},
  author       = {Berstein, Serge and Milza, Pierre},
  year         = {1998},
  publisher    = {Institutul European},
  location     = {Iași},
  series       = {Sinteze},
  volume       = {1},
  isbn         = {973-586-027-9},
  volumes      = {5},
  translator   = {Bița, Ionuț},
  editor       = {Zugravu, Nelu},
  editortype   = {editoranco},
  pagetotal    = {372}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
\nocite{*}
\printbibliography
\end{document}