I wrote a gradle-plugin to convert between Android translation strings.xml files and Excel which you can include your in android project:

android-translations-converter-plugin

With the task exportTranslationsToExcel you can export all your strings.xml to a single Excel file

With importTranslationsFromExcel you can import them back

Being a gradle-plugin you can easily automate it to run on every build or as a pre-commit. This is further described in the README.md