How to get babel's language shorthands work inside biblatex entries with autolang=hyphen and langid fields?

Question

I'm writing a German document, where I frequently cite works in English and other languages. Used to babel’s shorthands in ngerman for easily modifying hyphenation symbols in compound words or names (for example "= for an additional hyphen that should always be printed, and "" for a possible line break without a hyphen), I also activated those shorthands for english using the \addto\extrasenglish commands.

Inside otherlanguage environments in the main document’s text, everything works as expected.

biblatex, which I use for managing my bibliographies, offers the autolang option and the langid field for switching hyphenation rules for each bibliographic entry. When I set autolang to other, it puts an otherlanguage environment around the citations and bibliography entries, and therefore uses the shorthands. But it then also prints terms like and in English, which is not desireable in an overall German document. biblatex therefore offers the autolang=hyphen option to only activate the hyphenation rules for the language specified in the langid field, while falling back to the main document language for all other terms.

However, then the shorthands do not work anymore. How do I get them to work?

Here's an MWE:

\documentclass{scrartcl}

\usepackage{fontspec}
\usepackage[english,ngerman]{babel}
\addto\extrasenglish{\useshorthands{"}\languageshorthands{ngerman}}
\usepackage{csquotes}
\usepackage[backend=biber,autolang=hyphen,style=verbose]{biblatex}

\usepackage{filecontents}
\begin{filecontents}{bibliography.bib}
@collection{NMR,
  editor = {Wardrip"=Fruin, Noah and Montfort, Nick},
  title = {The New Media Reader},
  location = {Cambridge/""MA and London},
  publisher = {MIT Press},
  year = 2003,
  langid = {english}
}
\end{filecontents}

\addbibresource{bibliography.bib}

\begin{document}

\begin{otherlanguage}{english}
  Manually using babel shorthands inside an \texttt{otherlanguage}
  environment, everything works as expected: Wardrip"=Fruin.
  Cambridge/""MA.
\end{otherlanguage}

Yet, citing the work from the bibliography, where it was given a
\texttt{langid} field, the shorthands do not work.\autocite{NMR}

Neither do they work in the bibliography:
\printbibliography
\end{document}

Answer 1

The hyphenrules environment actively deactivate all language shorthands. But babel offers generic commands which always work:

\documentclass{scrartcl}

\usepackage{fontspec}
\usepackage[english,ngerman]{babel}
\addto\extrasenglish{\useshorthands{"}\languageshorthands{ngerman}}


\begin{document}

\begin{hyphenrules}{ngerman}
  Manually using babel shorthands inside an \texttt{hyphenrules}
  environment, doesn't: Wardrip"=Fruin.
  Cambridge/""MA.

  Use the babel commands: Wardrip\babelhyphen{hard}Fruin.
  Cambridge/\babelhyphen{empty}MA.
\end{hyphenrules}
\end{document}

biblatex has also the commands \hyphen and \hyphenate (but imho nothing for "").

Edit

Actually you can define the shortcut so that they work for all languages:

\documentclass{scrartcl}

\usepackage{fontspec}
\usepackage[english,ngerman]{babel}

\usepackage{csquotes}

\useshorthands*{"}
\defineshorthand{""}{\babelhyphen{empty}}
\defineshorthand{"=}{\babelhyphen{hard}}

\begin{document}
\begin{hyphenrules}{ngerman}
  Wardrip"=Fruin.
  Cambridge/""MA.

  \end{hyphenrules}

\selectlanguage{english}
  Wardrip"=Fruin.
  Cambridge/""MA.

\selectlanguage{ngerman}
  Wardrip"=Fruin.
  Cambridge/""MA.

\end{document}