Just to put some official word on this: we don't officially allow non-English language on the forum, but as pointed out we don't enforce this with an iron fist. The bigger problem is long discussions in a different language, which is inconvenient to moderate even with Google Translate. We do generally step in and ask people to use English where possible, but I suppose we occasionally miss some threads. I hope you don't see this moderation practicality as injustice, it's just a busy forum and sometimes stuff slips by.
Weishaupt, you shouldn't be upset if you perceive non-English speakers to be impolite - if they don't speak English they may have already struggled to write their message so this may have distracted them.