I think that both languages should be allowed, for questions as well as for answers. I suggest some rules on how to meet a decision:
Language of a question
Use German if ...
... you are a German native speaker
... your German is excellent, even when you are an English native speaker
... your native language is not English, and your skills in German are ...
There is a lot of detailed information from the help pages for Stack Overflow regarding privileges:
Privilege to vote down
Privilege to close vote
These guidelines are valid all over the Stackexchange network with only little variation amongst specialized sites.
In summary we may vote down questions or answers for the following reasons:
Fragen zur Etymologie sind grundsätzlich on Topic, wie auch Fragen zur Bedeutung eines Wortes im Kontext. Es gelten hier die gleichen Empfehlungen wie zu anderen Fragen.
Sollten Kommentare darauf hinweisen, die Frage einzugrenzen, oder sollten Fragen zu noch fehlenden Details aufkommen, empfiehlt es sich, diese zeitnah zu beantworten.
Fragen nach der Form ...
Nobody’s bothering to answer, so I’ll post my thoughts as an answer and see if it gets any votes.
Additions to questions are, of course, reasonable and allowed if posted within the first few hours, ideally before any answers have been given.
If there are no answers, late additions can still be allowed, as it shifts the question back up in the active ...
We did not mention this explicitely in the tour but if you scrolled further down you see a link to our help center. There you can read in the "What topics can I ask about here?" section:
Questions in both, English and German are welcome but note that posts on Meta should always be in English.
So yes, asking and answering in both German, and English is ...