I am walking the plank

[Branman123]

For the first few years of playing FFR, I played with the index fingers.

While that playing style was good back then, most of the harder difficulty songs are proving to be anti index to the point where I decided to learn spread (ASKL keys).

The part where I am lacking on spread is my left hand namely fast down and left trills. Any good songs that would help me improve the coordination with my left hand or should I rely on good luck?