Pandry
But this would mean that every user should know all the other languages...
In my opinion, there are too possible issues.
No it will show just the language according to the locale used in the website.
If the Language is english it will show just
[EN]Hello I am a post.[/EN]
and if the user switch the language from the language switcher on the top of the forum it will show the other language content
for example
[FR]Salut je suis un article.[/FR]
But I think the best solution is : to use for each language a column in the table database..
so the users for each lang can use the contents of the lang that they are talking it