"Correct" way to monitor custom events?

[Din]

So, probably a stupid question, but is there a "correct" way to handle behavior dependent on custom events in oUF?

By which I mean, say for instance I want to tint the target frame's backdrop based on unit reaction. This obviously needs to be updated on a target change and also on (I think?) UNIT_FACTION. Should I just be directly registering for these events and handling the behavior in my own functions, or is there some sort of hook/register/postupdate system oUF has that I ought to be using?

Obviously if the thing I wanted to change was a text string I'd just use tags... and I briefly considered abusing the convenience of the tag system for these purposes but I'm guessing that's not a good idea.