Well, at least in Germany, English is not always taught as second language in school and I know many people who can't read or speak English very well because they learnt it too late and don't have it around every day.

I'd suggest that people should be advised to use the English forum here unless English is a problem.
That way the people who don't speak English well have a place where they can ask questions, but the subforums wouldn't get too crowded which makes them easier to maintain and helps avoiding fragmentation.