So I may be on to something. First of all though I noticed that if you just take a voronoi, and than a merge shader with the A input being a transform of the voronoi with a rotation in Y by 45 degrees or 90, and a scale of 2,2,2 it gives a very similar look to what you show here in displacement.

I'm currently trying to mix a X,Z square noise with a Z,Y square noise with voronoi, and than stratifying on 0 degrees and 45 degrees with variance. Rendering a test now.