I just tried 2.1 version and currently I found 2 bugs.
1. The light doesn't appear on every note for fast passage. I'm not sure if its related to the fps setting. Here is the video which have this problem, not quite obvious but noticible if you pay attention to it.
2. When i render the video, the last notes still seem to get cut off. For this song, when i render it the video is finished before the particle disappear. So the last frame stopped while the particle is still there. I have to create a longer midi with some extra notes after that to avoid it. Not a big issue but i think it's probably still related to the play speed in the app which caused that?