The HP for the other 2 sizes of the Maw-Ray seem to work properly (Small Size having 15 HP, and Normal Size having 20 HP). However, the large one should be at 30 HP, but it only caps it at 20 HP, whether naturally spawned or spawned in via Creative Mode.

Here's some screenshots of a naturally spawned large Maw-Rays HP:

MC Version: 1.20.1
Forge: 47.2.0
Super Block World Mod Version: 0.0.8-1.20