Hi on my MC server I use Firstaid as the main health system. over the last few days I have realized that the mod sometimes well how shall I put it in words

for examlple I join the hub with like no head and body and arm. thats an issue for me is there a way I can heal players directly on join?

FirstAid diggs very deep into the minecraft data manager to intercept all health changes. Because of that, it makes some assumptions that are valid for forge servers and other mods, but may break with custom servers. Last time I looked these custom servers had some weird code around the health changes. My stance has and will always be to only support forge and no custom servers, as it would mean a ton of work for me to fix firstaid for these custom server and I would have to make sure that nothing breaks there as well for every version. And yeah, that's not something I am going to do. Sorry