I have been playing around with YPhil's setup and made some node modification that addresses the odd bump/displacement behavior we're seeing on the right side of the face.  The image below shows the new shader node arrangement within the Vascularity compound node.

I am predominantly using the Veins Diffuse map to generate the bump/displacement maps.  The screencap below shows the Material Room arrangement for the face.  IIRC, the original product used both the Bump and Displacement channels to elevate the veins on the skin surface.  I still don't know why one side of the face renders correctly and the other side not but I managed to find the approximate combinations to make the displacement work.

My Poser units is in Feet and the particular skin texture I was working with did not contain a bump map so I had to improvise.  Note the values on the Bump node, they should remain at those values for this to work.  Control the amount of displacement on the Vascularity node, using very wide ranges to exaggerate the veins will cause the artifact to appear again.  If the balance is achieved, you will get the results below.

It's not perfect but the shadows are appearing in the right direction.