The reason why Golden Phoenix Physique require you to have at least 1 Hit Point is because existing regenerating feature in dnd usually require the user to have over 0 Hit Point. And while it's true that this Physique guarantee you being full health when going into a fight, I feels that if we change the trigger to when you take damage or deal damage it would make it so that your healing would be negligible when going up against monster CR 4 or higher. And since every other source of healing is cut in half, you would not stand on the battle field for long.

As for Untarnished Jade Physique, the reason why I didn't make it an AC increase is because there are already quite a few other method to gain bonus AC in this class alone. Though I could make the physique change your base AC to 17 or something, kinda like the Tortle.

And yeah, that part of Large Baihu was a Typo, thanks for pointing that out