This is a follow-up to
While the main site should accept both German and English questions, and you should be able to ask in the language you are more fluent in, what should be the preferred language if the person asking the question fine either way?
I can imagine that there are quite some users in the community that could provide better answers to a particular question if it was asked in German/English as opposed to English/German. So maybe an indicator when to ask what in which language would be appropriate?