Jumping in because multilingualism online is one of my pet topics (if anybody reading this ever saw one of my “Waiting for the Babelfish” talks, do come say hi, it’ll be a blast from the past!) – and I wanted to second this idea: most people are imperfectly multilingual. I’m a French-English bilingual, and my German is decent. Decent enough that if I’m in a community where people are speaking German, I’ll try and read the German first.
FWIW, in my professional (multilingual) environment, we use Viva Engage, and I quite like the way it manages the translation issue: if you’re looking at a post or comment that isn’t in your language, you see a little “translate” link at the bottom which immediately translates it in place. Kind of like on Facebook.
Ideally, as a user, I’d like to be able to say “never translate French or English; for German and Italian and Spanish, give me the translate link; for other languages please translate directly and give me a link to revert to the original”
I could quite conceivably imagine managing a French-English community with a handful of German and Italian speakers (a realistic scenario for Switzerland), and I would definitely not want to have either French or English translated.