I'm not sufficiently fluent in Spanish (Castellano) to attempt this in Spanish, but I think this is a matter where each contributor writes in the language or languages in which the writer is fluent. I would think that if I saw Lengua (Lenguas) that many or all of the posts in that interest would be written in Spanish and would be from people who are interested in Language as a subject.
The problem would be with the interface. The icons are pictorial but the tooltips are English. The words Follow, Cancel, and Reply are also English.