There's a big difference between a static Wikipedia article and a dynamic topic with back and forth posts. Yes, you can translate a static article into multiple languages. But how would a forum topic go? Would a user voluntarily provide multiple language translations for one post with multiple responses from multiple people with multiple levels of language skills? Wouldn't that lead to fractured and broken conversations? You can't have post #3 available in English and German, but post #4 available in only English, and post #5 available in German and post #6-9 available in Esperanto. Even in Woltlab, they don't mix the German and English in ONE discussion item. They have completely separate boards.