To fix the negative edge commands in Bull Head, you have to go to the special, find the part that changes the strength depending on which button is pressed and add the code to make it do the same on button releases.
So, instead of this
[State 1001, Varset]
type = VarSet
trigger1 = Time = 0
var(10) = ifelse((command="y"),1,ifelse((command="z"),2,0))
IgnoreHitPause = 1
Persistent = 1
it reads this
[State 1001, Varset]
type = VarSet
triggerall = Time = 0
trigger1 = Time = 0
var(10) = ifelse((command="y" || command="rlsy"),1,ifelse((command="z" || command="rlsz"),2,0))
IgnoreHitPause = 1
Persistent = 1
There's also a small mistake in the move list for The Birdie: both versions show *Hold* B, F, B, B instead of *Hold* B, F, B, F
Pretty good update otherwise.