The QGraphicsTextItems / QGraphicsSimpleTextItems were corrupting themselves on Android. I fixed it in 

By adding  item->setCacheMode(QGraphicsItem::DeviceCoordinateCache);  for all items.

I noticed that problem (text corrupts in QGraphicsTextItems, but not object labels) seems to match at least one bug report for desktop Stellarium. Could the same fix work there? I've no idea why it worked in the first place, it may just be specific to Necessitas, but I thought I'd throw it out there.