biblatex date string not defined with Greek and autolang=other

Question

In answering this question I discovered some strange interaction between the greek language setting and setting the autolang option of biblatex to other.

As you can see from the output, the month gets output as dateapril because that bibliography string is undefined. If I change the main language to something other than greek, e.g., german or french the problem does not arise. But since the autolang=other option should be accessing the english date strings (as it does with these languages) it's not clear to me why when greek is the main language, the date string is undefined.

The following document reproduces the problem.

\documentclass{article}
\usepackage{filecontents}

\begin{filecontents}{\jobname.bib}
  @article{anarticle,
    author={Lathrop, J.W.},
    journal={Electron Devices, IRE Transactions on},
    title={Photolithographic fabrication techniques for transistors},
    year={1958},
    month={4},
    volume={5},
    number={2},
    pages={117},
    doi={10.1109/T-ED.1958.14395},
    ISSN={0096-2430},
    langid={english},
    hyphenation={english}
  }
\end{filecontents}
\usepackage{polyglossia}
\setmainlanguage{greek} % works with german, french, etc.
\setotherlanguage{english}
% Change these if you want
\newcommand{\MainFont}{Times New Roman}
\newcommand{\MonoFont}{Courier New}
\setmainfont[Mapping=tex-text,Ligatures={TeX,Common}]{\MainFont}
\setmonofont[Mapping=tex-text,Ligatures={TeX,Common}]{\MonoFont}
\newfontfamily\greekfont[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\MainFont}
\newfontfamily\greekfonttt[Script=Greek,Mapping=tex-text,Ligatures={Common,TeX}]{\MonoFont}

\usepackage[style=alphabetic,maxcitenames=2,language=auto,autolang=other]{biblatex}
\addbibresource{\jobname.bib}
\begin{document}
\cite{anarticle}
\printbibliography
\end{document}

Answer 1

The problem turns out to be a bug in the greek.lbx localization file. Instead of using its already defined \lbx@gr@mkbibmonth to format the date, it instead uses \mkbibmonth defined via \let\mkbibmonth\lbx@gr@mkbibmonth after first using \savecommand{\mkbibmonth}.

Replacing the use of \mkbibmonth with \lbx@gr@mkbibmonth directly in the .lbx file solves the problem. I have reported the bug to the author, and the fixed file will appear when the next update of biblatex is pushed to CTAN.

Answer 2

Add in preamble:

\DefineBibliographyStrings{english}{%
  dateapril = {April}
 }

Now result is :