Then you workout those special details at the Refine Details step 3

https://www.youtube.com/watch?v=yGybHOGOqoQ
https://www.youtube.com/watch?v=VcXce1O_eT4

What if the high poly mesh was retopologized/shrink wrapped externally using a CC base to include those finer details while retaining the correct face count?

Yes, something like a face scar refined with hi-poly geometry would certainly be baked into normal.

So this is what determines what ends up as normal map details vs. geometry?

It may not be part of the geometry because all standard CC characters must have strict/same face count and it cannot add more geometry on the fly to accommodate for every curve and creases.

These are from a Headshot character:

Headshot 2 captures the overall form of the mesh pretty well, but certain details that add to the likeness like creases and skin folds are being represented through a normal map. It doesn’t look as good as when those details are part of the actual geometry. Any idea why Character Creator relies on normal maps for finer details? It’s fine for fine wrinkles and pores, but it would look better if the details I mentioned above were part of the geometry.

@bennydee Looks like you may have meant to post this as a new question / discussion but it got posted as a reply.  Maybe?

--DRLarkin

Fairly new myself so I'm not 100% sure but I do believe the finer details are presented via normal maps. 
Have you tried increasing / decreasing the strength of the normals? 
Which details are you referring to specifically?
Do you have SkinGen?

--DRLarkin

Failed to create MDL shade node for prim

So I’m getting the following message in the console:2023-06-19 12:42:36 [Error] [omni.hydra] Failed to create MDL shade node for prim ‘/World/Looks/Ceramic_Tiles_Subway_Antique_White_Dirty_02/Shader’. Unsupported identifiers.This happened all of a sudden, out of the blue. Materials were loading fine, and the next second, not. I also tried to export the MDL and re-apply the exported MDL but it seems that there are issues with exporting the MDL too.Is there a fix for this issue please?Thanks in advance!