This repo is no longer an independent component. It is a submodule of the Magisk Project.
The default (English) string resources are scattered in these files: src/full/res/values/strings.xml, src/main/res/values/strings.xml, src/stub/res/values/strings.xml.
Place the translated XMLs in the corresponding folder to the locale.
Translations are highly appreciated via pull requests here on Github.