Of course there’s no engineered homeostasis to mess up on Earth. There might be a general tendency toward homeostasis: lots of, in some generalized sense “mass” and “momentum” in the system, and a tendency for species to die off by consuming all their resources and running out of places to put their byproducts. But that seems more likely to be something that humans fall afoul of, not coral, which seems more like an accidental victim and evidence that homeostasis has some pretty big gaps.
I think you need a larger picture - think system theory, and think about multiple overlapping equilibrium biochemical reactions going on all the time. Even in your own body to maintain homeostasis. That's scaled up on a global scale.
How key are coral? Do you know? If you don't you probably shouldn't mess with it. Heh! :)
