There are now some app specific reports in http://mobile-reportcard.wmflabs.org/#apps-graphs-tab. Since it takes quite some time to load them when there together with the other reports on the same dashboard I made them also available as a separate dashboard: http://mobile-reportcard.wmflabs.org/dashboards/apps.
The first three reports are about app edits showing the various stages of the edit workflow: one for both Android + iOS total, one for Android only, and one for iOS only.
The next four reports show basically the same data but from a different perspective: how many times edit got clicked, preview, save attempts, successful saves.
The last report shows the number of blocked "app users" on English Wikipedia. For this report you are considered an 'app user' if you've created the account on the Android or iOS native app.
Enjoy, Bernd