According to this chart we have 100% of our strings translated in only 14 languages:
https://translatewiki.net/wiki/Special:MessageGroupStats/?group=out-wikimedia-mobile-wikipedia-ios&x=D#sortable:3=desc
Android has 100% in 7 languages:
https://translatewiki.net/wiki/Special:MessageGroupStats?group=out-wikimedia-mobile-wikipedia-android-strings&x=D#sortable:3=desc
Note: the relative `100%` count probably fluctuates as new patches make string additions/modifications. e.g. this week iOS has more, but next week Android may have more depending on how quickly translators churn through respective changes. Of equal interest are the languages nowhere near 100%.
One possibility would be to identify active translators in respective langs and reach out to them providing TWN links to our apps TWN strings groups.
It could be that with relatively minimal effort on our part we could greatly improve our apps' experience for a large number of people.