Recently I've been experimenting with customizing the language strings for Moodle Mobile. So far I've had mixed results depending on the language string identifier. For example, I was able to customize "Back" in the app header by adding mm.core.back|戻|ja to the custom language strings area of Site administration/Mobile app/Mobile features. However, when I attempted to customize "Submit" in the Lesson module by adding mma.mod_lesson.submit|次|ja it didn't work.
I tried refreshing the page, logging out of the app, and deleting and reinstalling the app. None of these things had any effect.
I got the language string identifier from the list located here. Is there something I've done wrong?