I fully agree, Osmand is so close to being great. It's clear that a ton of work has been put into it, but has a few major flaws that make it nearly useless. It's the first open source project I've considered contributing to, and I might do it soon.
* The jank you mention - it was one of the first things I noticed as well.
* Search just doesn't work. They have addresses and POI in their database, but for whatever reason, search strings don't match, and addresses don't work at all either. It's completely broken.
* Really needs the ability to toggle direction mode, i.e. always pointing north, or pointing in the direction of travel or the device's compass.
I also would like to add a couple improvements that are not really flaws with the app:
* Ability to record GPS path
* Ability to share recordings/trails - would allow me to get rid of AllTrails