***Most certainly NOT your standard "dark texture" issue...
I've spent a lot of time learning how to properly import and export .nif files from Blender, and dancing around all the little caveats that go with using old, outdated codding, because there is nothing up to date to use. Imported the head I wanted to work with, set up the vertex maps (skin partitions), weighing, bones, etc., exported back out as a .nif, made the proper adjustments in nifskope, and everything's looking fine... until I put it in the creation kit.
It shows up in Creation Kit with a darkened texture, and if I check "SLSF1_Facegen_Detail_Map," then Creation Kit crashes when loading the .nif .
I've done all the standard checks for fixing darkened textures:
Has Vertex Colors = yes (also checked off in the shader properties)
BS Num UV Sets = 1
Has Normals = no (I've tried it with "SLSF1_Model_Space_Normals" both on and off)
And very large number of variations and combinations in between, including, but not limited to, playing with the alpha values, import/export settings on blender, the emissive color/multiplier tags, setting vertex colors to no, setting uv sets to 4079, etc.
I've also tried copying the NiTriShapeData and dismemberment data into and over the same data sets inside the .nif file of a working head, but this (not surprisingly) results in other complications. Although, there are a few more variations on this I could try as well...
From what I can gather, this almost certainly relates to the facegen data, or absence thereof, since it's a custom face mesh (everything else works, it will even load in game without issue). The only solutions I've found for facegen data not running correctly involve custom actors, and not custom races (which doesn't have any actors).
My knowledge on facegen data is extremely limited. Is this something that's supposed to be baked into the head mesh .nif file? Is there some special extra set of steps, specific to editing/creating head/face meshes, which involves special data sets that are embedded into the mesh? The settings for a mesh in nifskope, and the fact that having it turned on crashes creation kit, certainly seems to imply this...
Side note: what would you guys recommend using to post images (screenshots) and download options for the related files?