Apps are translated through Weblate: a free web-based translation management system.. In order to submit translations, you should:
Once you’ve selected a project, you can provide suggestions for strings that have not yet been translated, or suggest changes to strings that have already been translated. These suggestions will be evaluated by a translation team member and they will choose the most appropriate one. For a more information about Weblate, you can refer to their documentation.
If you don't want to use Weblate, or want to make a lot a changes at once, you can also translate offline. To do so:
如果你完成了你的翻譯工作，你可以在下載原文件的頁面中選取 “上載翻譯文檔” 來上傳你的成果。
For more information about Weblate, you can refer to their documentation.