I'm not entirely sure but I think it said in the invitation to the interview (unfortunately, I don't have this document anymore) that documents in an official language of Switzerland would be accepted. And I think this is also stated in the invitation to the interview in Germany (maybe someone like Tazmania could enlighten this).
I agree with you, raevsky, that certain documents will need to be translated at a later point anyway. However, certain documents will probably not be needed again, or it might be easier to do it in the US (I don't know about that). I was lucky: So far I have not needed any translations.