This will not work.
User who speak english do not care about such section and user who do not speak english will leave this place before they find said section.
Also IF there is a post there, none will blend it out, we will just try to impress with the barely readable 2nd or 3rd languages we learned at school.
Instead of one matzesu per thread, we get a thread full of matzesus. (Sorry dude, could not resist the analogy )
Dunno about that, internet forums are probably the reason I learned to write/read English in the first place.
Communicating with people is the best way to learn a language, so using "Welcomes people with poor language skills" as reason is not good I think.