I know how to. But only in Ren'py. Sorry if I'm late and you already found a solution!
Basically, you just put:
if num_notes > 145:
Then you can make different routes. the number of notes is in the beatmap at the end of the long one of decimals. (Basically the number at the start of the last string of numbers in the beatmap)
The '>' indicates 'more than'. If The player got more than the beat number you put in, then the will go that route. Similarly, you can put:
if num_notes < 145
Then players that got less than the number you put in would go the other route. You can do this with other objects too! Like affection points and stuff like that.
define points = 0
Put this before 'label start' if you want to use it for anything else.