English string resources are saved in the localization module's strings.xml file. Those English strings are then translated into the other languages we support through https://translate.wordpress.com/projects/pocket-casts/android/. We update the translations for all languages other than English from translate.wordpress.com each time we cut a release.
This means that only English string resources should be edited directly in this repo. All other languages will get updated from translate.wordpress.com as part of our release process.
If you're interested in helping to translate Pocket Casts you can contribute at translate.wordpress.com. This page gives an overview of how to get started: https://translate.wordpress.com/glotpress/.