Am I missing something or is it not possible to view all tracks you completed at a certain difficulty level? I would like to complete all songs on expert but it's pretty difficult to get that information. The highest score shown when you select a track is sometimes from a lower difficulty than the highest difficulty I completed the track in. The only way to be certain (as far as I know) is by checking the leaderboards panel next to the song info, which wouldn't be so annoying if it would default to the second tab (self instead of global).
Am I missing something or is it just really annoying to get info like this?
I also think the playlist feature is extremely unintuitieve to use. Why isn't there an 'add to playlist' button when you complete the song for example. I love the game but feel like the UI could be polished a bit more.