I edited an NPC beautifier and now I have a neck seam - Help resolving?

[DalinarGeneral]

I made a few edits to AZ's Song of the Green Auri replacer (https://www.nexusmods.com/skyrimspecialedition/mods/26084). I'm trying to give Auri a custom body mesh and texture path for body slide (successful), and to give her the DXDruid armor (also successful). When using the default CBBE body textures, everything looks good: https://imgur.com/n2xMAZY

However, I'd like to give her a more toned appearance so I wanted to replace her skin texture with the Bijin skin. I used the Bijin CBBE skin for all four body, hands, and face textures as well as the "frekles" texture. As soon as I did this, it caused a neck seam: https://imgur.com/ED0oh3g

I don't understand the cause; as far as I can tell all of the paths in the esp are pointing to the correct files: https://imgur.com/rdBA1cF

I tried opening my esp in the creation kit and exporting Auri's facegen, but she ended up looking like a (horrible) version of the original 018Auri.esp master file both in game and in the CK preview (https://imgur.com/a/5MDB9Gh). As a test, this also happened when I opened the original AZ Auri plugin in the CK as well; for some reason it doesn't seem to be reading the extra assets used to make the replacer.

Does anyone have any suggestions for how to fix the neck seam, or why the CK isn't able to open the follower correctly? Thanks, and I hope this is the right forum for "mod creation tech support."

[DalinarGeneral]

As soon as I posted this I had the bright idea to open the facegen mesh in NifSkope - I'm no expert but after some clicking around I found texture paths referencing femalehead(*).dds. When I changed those to my desired paths, which pointed to the Bijin skin textures, it actually fixed the problem and I no longer have a seam. This seems like an obnoxious way to fix this though - for my future reference, could anyone tell me why the CK isn't properly loading Auri's appearance with this plugin?