Good question! Sadly no, storing that kind of fluctuation would cost way too much in space to be done in L1. But could be done via L2 in an external db that tracks all the transactions and calculates each time. But it's gonna be quite a challenging project.

I think to identify abuse you could look every say, 5-6 hours and check which are the accounts with low rc out of all the ones you delegated to, and if one dude is always at 0 current rc that means he's either very active using a ton of rc or an abuser.