Hi Martin,
your idea is well-conceived 
In fact, there’s no need to explicitly record anything as Sonic Pi already automatically records the most recent events for you and stores them in the time state system.
However, where Sonic Pi falls short is providing you with simple ways to work with that existing automatic history of events.
Therefore, would it be possible to sketch the kind of code you’d like to be able to write and we can use that as a starting point for a discussion. I think it’s much easier to discuss where the end point would be for you and then figure out how to get there together with you then verifying whether the implementation(s) we come up with actually do help you