I have certain sprites coming into and out of existence programmatically all the time, and usually their exact animation timing is independent and doesn't matter, but now I have a few that I'd like to be perfectly synchronized.
I think from both your suggestions, the idea is that I could just manually track it myself, for each sprite. Yeah, I think that's possible I suppose, but darned inconvenient. The thing is, there already exists a tracking counter for each sprite within the Roku system, we just apparently don't have access to it!