Hi Marta!
We welcome any and all contributions to our translation effort – it is however very much a community driven process and we rely on speakers of other languages, like yourself, to pitch in with translations 🙂
There is (I believe) an existing Catalan catalogue within the plugin (lang/tribe-events-calendar-ca.po) and if it needs work please don’t hesitate to let us know of any mistakes (along with possible corrections) and/or any missing entries.
You can share these across on our Translations Forum.
Thanks again!