you could try,
is falling + is overlapping ground at offset (-10x, -5y) -> Set animation to "fall drop"
ELSE + is falling + is overlapping ground at offset(-10x, -5y) -> Set animation to "fall drop"
ELSE + is falling -> Set animation to "fall roll"
The conditions won't be exactly like that I think, but I think there is a check for overlapping at offset in CC. Hope that works!
Edit: Also add a check to all three to make sure the player isn't already playing animation "fall drop" or "fall roll", so it only triggers once each time they fall (make the drop off platform fall a looping animation even though it's a single frame).
And you might need to remove the tag "Falling" from the roll fall, since the events have to override it.