I'd like to make natural regen only give back part of the overall health bar. For example, when hunger is full you will regenerate helath, up to 6 (3 hearts) but will need to sleep to restore health back to full.

That's a great idea. I'll have the code open for a bug fix for forge 1.20.X soon.
I think adding your requested feature will not be hard for me nor confusing to users.
Complexity seems low. I'll probably add this soon (the next 2 to 10 days).

What version of minecraft are you running?

Hello !

I was going to open a similar topic, but more in the sense of being able to choose a regeneration in 2 steps ^^
For example, deciding to regenerate life at 6pv at a rate of 1pv/s, then 0.25pv/s for higher values:

healingPerSecond = 1
maxHealing = 6
healingPerSecondAfter=0.25 

Then, if it's not too complex to set up, consider using a table for more freedom of customization:
healingTab = [ "1|6", "0.25" ]
This would be useful in adventure modpacks where the max life often exceeds 20 and where you want to make the levels more complex:
healingTab = [ "1|6", "0.5|12", "0.25|24", "0.125|32", "0" ] - (The final “0” would stop regeneration)
But since the mod also uses commands for configuration, I don't know if setting up the table is really possible ^^'.

Anyway, thanks for your mod and good luck !

P.S.: I'm in 1.20.1, so let's see if it's possible to implement this feature in this version ^^

It looks like I was unable to act on this back then. If I'm able to add this feature, it will go in 1.21.4 first. And then I'll see about backporting it to 1.20.X.

I've had some health issues ( Covid and Long Covid (which has finally cleared up) ) that have put me about 3 to 4 months behind schedule.