Yes, but in this way I will translate only my game, if I would translate in a way that Kael and the team can use my file to give an extra language to the game?
Talk to the development group, but it's very likely that if you translate a significant percentage of the files into Italian (I think he prefers it in the .xls file), and post it, it will probably be included in a future release. You can look at the other non-English language threads; they may be of use for format, etc.
My approach would be to read those threads, then start an Italian translation thread with, say, a small portion translated. Wait for feedback, then translate more.