Mastalab works only with Crowdin, which offers nice tools for helping in translations. New translations will be automatically merged in a branch. If your language is not listed, please ask me to add it. If you prefer to work on an XML file, you should be able to upload it with Crowdin. Crowdin will not pick up changes in develop branch, that’s why all translations should be done with this tool.
If you’re submiting a merge request and your work adds new strings to the app, make sure they only exist in the default strings.xml file (res/values/strings.xml). If you add or modify strings of other languages, it will interfere with crowdin’s translations.