That is not the same problem, the back of the head and face use two seperate textures. Face uses generated textures based on vanilla face textures, cbbe skin textures or any other custom textures will need to be added by regenerating npc face textures. Also, you need matching face and head textures for the back of the head to be seamless. The UV map for the back of the head is fine, it's just the texture needs to be edited which is a completely different thing to fix.
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Other things still need to do for mods:
This is the main, there might be a few other broken or inconsistent things to fix to.