If you deleted the RBHP upgrade package but didn’t delete your cache, you’re looking at stale song data. Also, the game likely will crash if you try to play harmonies in a song where the upgrade no longer exists.
As best you can, let me know what 2010 songs were’t working, or at least some examples, and the steps you took when trying to add harmonies to them.
You are about to leave Rhythm Gaming World and access the external songs DB. While no song or file sold for commercially available videogames is hosted there and only fan generated content is allowed, Rhythm Gaming World has no direct control over the database and no files are hosted here. Alright, we had to made you aware of this, now you can visit the database!