The settings translation key that denotes the Amecs Skin Layer tab is broken and shows its registry name. I was able to fix this with my own en_us.json by just removing the amecs from "amecs.key.category.amecs.skin_layers": "Amecs Skin Layers", and leaving it like this "key.category.amecs.skin_layers": "Amecs Skin Layers".
without my resource pack
with
