Mod version - 1.6.22 for NeoForge.
While editing the mod config, I noticed that you can enable full set bonuses for armor. I set all of the full_set_bonus parameters to "true" and reloaded the game. When I re-equipped the amethyst armor set I had and jumped from a cliff, I still took fall damage.

I see the problem. I will get an update in a little bit.

it affected all three sets.

version 1.6.28 has been pushed to cursweforge and fixes this issue.