The way the number of points decreases along the Z-axis

as far as i understood your sketchs you want to creat a diamond pattern rigth?
i found a solution if you treat´the sides seperatly (21.7 KB)
found it in the primer

found a solution for the whole surface:
i set the graphmappers range to 0.5 “mirrored” the results and merges them.
This script is based on the surface UV so i you are having a problem on other surfaces you migth need to swap UV in rhino with the direction command - hope this helps. (53.1 KB)