I'm sorry, but it looks like you are misunderstood my question. I'll try to explain it in more detail.
So, for example i have 1 forum with 3 names in 3 different languages.
And we have some topics in all that languages collected in this one forum.
If user will be able to specify his language in the editor(when he starts a new topic), we will get one more field for filters and sorting. Then all other users will able to show/hide only topics with a specific language (or not indicated).
Sorry for my English.
