This doesn't make sense Thomaslaw. Re-read it.
You are arguing that "Chinese TianTai and HuaYan Buddhism" believe a completely redundant doctrine: that phenomena manifest in the mind. Very profound, said no one.
The mind can be metaphysical or ontological if you want it to be. No one's the boss of you. If you want to be a Huáyán Buddhist, and believe in mental ontologies or metaphysics, go for it.
But what you wrote literally doesn't make sense. It made more sense when you were accusing these sects of believing that all minds are the same mind. Or was that what "all-emcompassing" was supposed to mean?
Also: prove it. Whatever it is. If it even can be proved.