Hi, and thank you for your interest!
Kopano is being translated using Weblate, a web tool designed to ease translating for both developers and translators.
Translation project for Kopano into German currently contains 2953 strings for translation and is 95.8% complete.
If you would like to contribute to translation of Kopano, you need to register on this server.
Once you have activated your account just proceed to the translation section.