Comment 4 for bug 1673258

Would be quite cool to make the language-selector use "localization" AppStream components to detect missing locale... That would also make it work easily with PackageKit.
=> https://www.freedesktop.org/software/appstream/docs/sect-Metadata-Localization.html

This would require some bigger effort though to generate the appropriate metadata (I will look into it though, since long-term I would like to have a solution like this at Debian as well).