For help on translation tikiwiki into Catalan, check so far the information posted at:
http://www.moviments.net/tiki-index.php?page=TikiwikiCatala
And the state fo the art of the translation, at:
i18n status
We are a bunch of people working on the Catalan translation since 1.4, but unfortunately we never finished completely (100%) a language file of any tiki version, and that's why we never released the language file to tiki dev. team. We plan to deliver the file soon in a completed (or nearly!) version.
Cheers // fins aviat.