After reading some forums, I figured out how to create a multi-language store. So I created 3 stores (one in Spanish, one in Catalan and one in French) and installed the 3 packages too.
The language menu bar appears correctly displaying the 3 languages but so far only the Catalan dictionary works properly while the Spanish and French menus remain in English.
Of course, I did every possible refreshing and cache-cleaning and still the same. The strangest thing is that the Catalan menu works perfectly!!!
Does anybody have a clue?