Hi, and thank you for your interest!
Liberapay is being translated using Weblate, a web tool designed to ease translating for both developers and translators.
Translation project for Liberapay into Italian currently contains 799 strings for translation and is 94.6% complete.
If you would like to contribute to translation of Liberapay, you need to register on this server.
Once you have activated your account just proceed to the translation section.