In English: those sites are meant for people of all nationalities to learn the corresponding language, hence English should be used as a meeting point so that anyone can understand anyone else, especially when clarifying complex concepts concerning the language
In the corresponding language:
- Sites like those are meant for native speakers to clarify curiosities about their idiom (and they could very well not know English)
- People having questions about a language should be able to speak it already at an elementary level at least, and writing about it in it helps to practice it
- People helping in those communities and having wider knowledge of a language could not perfectly know English as they are specialised in their own idiom, and won't be comfortable in expressing complex concepts in English
I know there probably isn't an official way and both are good, as clarified by German Language's description, but which approach is preferred and more indicated? If I can do both, which one should I prefer when asking a question? When answering, should I write in the language the OP chose? Or
- Do both if you can, native first and English below?