If its as good as it looks it would add alot more nuances to playing a bard.
Bard Songs
Considering these bard songs are about the equivalent of fifth to ninth level spells, mass keen edge, mass rage, mass mage armor I'm going to come down and say they look horribly over powered from the descriptions alone, I'm unsure if that holds up if you view the full scripts but estimate it just gets worse.
If the balance was dived into and tweaked, I think this could actually be pretty spiffy!
Playing different songs for different occsions would be better than simply playing the same song and getting X buffs.
I prefer the more flavoursome multiple songs with different "themes", using some widget to choose what song you're going to play.
A song of mental vigilance (a significant boost to everyone's will saves) A song of fluidity (a significant boost to everyones reflex saves)
A song of Resilience (A significant fort save bonus)
Also dont forget the curse song versions which would reverse these effects to all non-party members in the area.
You can only be playing one song at a time, and if you play another the previous bonuses would be cancelled. (not sure how you would achieve that)
Then let me be the first to say that I don't like it. It makes bards seem too much like wizards, and Bard Song already is rather powerful at the higher levels. I don't think you need to be able to focus on certain aspects (saves, skills, etc.). Besides, right now it already works as it does in PnP.