Really dumb question - but how does the phone know the distance from your phone lens to your telescope lens? I assume this varies greatly from mount to mount and will change how accurate the app is?
The distance doesn't matter, since the stars are almost infinitely far away, so there's no parallax. You do need to correct for the angle though. We support daytime alignment using, say, a distant treetop, or at night align on the object you are observing.