All Xml files for every language
It's a public archive, so everyone can contribute to it.
If you are on the MCCallouts-Translation page [https://github.com/yasd2/MCCallouts-Translations], click on 'Fork' on the top right to create a local copy to your account. Then chose the files you want to edit. Next click on 'Commit', this only saves the progess locally in your fork. If you want to upload it, go again on the main MCCallouts-Translation page [https://github.com/yasd2/MCCallouts-Translations] and on the top click on 'Contribute' -> 'Open pull request', then I will get a notification and I can finally allow it to upload.