Especially after the redesign, there are many strings that are simply not used anymore. Those should be removed.
One could also move more translations to use the nested style instead of being at the top level. The redesign started doing that, but didn't change it for old strings.
Finally, unfortunately some languages are really almost non-existent anymore. Makes probably sense to remove those if we can't find someone who wants to translate it again.
Also see #1072