I use the Windows app Drawboard beside Kami, since it offers a much better annotation/highlighting experience.
Kami’s hightlighting feels stuttering, since it marks every letter alone and shows different color intensity when this hightling boxes overlap - Drawboard instead create one smooth straight line, like with a real marker.
When highlighting in Kami, it happens very often, that you move the pointer just a pixel, and instead of marking one more character or word, it marks the whole document. (This is a bug)
That’s how it should be >>
That’s how it is: when moving the cursor a bit on top of an already existing annotation or when highlighting over a link. IT just hightlights the whole page >>
Since this is your core functionality, you could try to improve the user experience before implementing cool new features.