Hi, and thank you for your interest!
MyPaint is being translated using Weblate, a web tool designed to ease translating for both developers and translators.
Translation project for MyPaint into Esperanto currently contains 1186 strings for translation and is 21.2% complete.
If you would like to contribute to translation of MyPaint, you need to register on this server.
Once you have activated your account just proceed to the translation section.