I can't cancle the EntityRegainHealthEvent with this code. Why? [BUG?]

You wouldn't go to a Debian forum for help with CentOS libraries, and you certainly wouldn't advise them to switch distribution if an application doesn't work as expected, at least not on their own forums... If there is a real issue with PMMP that you can reproduce then you should report it on GitHub and they'll check it out asap - you won't get that elsewhere. As for the no-spoon-talk rule, the APIs are growing further apart daily which means it is impossible for the staff to support both, and any threads that break the rule just confuse the issue even more for other users; so it's not rivalry, just common sense really.