Reply to One method to Easily Solve the language issue
I think it would be better to have the main forum English and then have a section dedicated to other languages.
Layout would be:
Main Forum (English)
Forum Section (Other Languages)
Sub-forum:French
Sub-forum:Spanish
Sub-forum: XXXX
The above is one of the more succesful ways I seen it done on other forums I been apart of in one form or another.