As I read in the Tour, this site is not only dedicated to translation from or into German, but also to discussing the finer points of the language.
Is it okay if German native speakers asks questions in German?
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 welcome here. Look around and you will see many questions and answers in German. We have however a loose policy to try to answer a question in the language it was written.