Pufferfish curves by curves on surface

as you can see in panels there is a few +/- in z axis of new curve by Pufferfish and it seems that is due to pull force of new curves on the nearest point on the surface face.
is there a way to manage this?somehow to force in xy plane not in xyz space
i tried projection of each curve through a mean but they will change in overall shape in some of my case.
currently i can avoid using distance in default contour.
thanks in advance

pufferfish-test.gh (11.8 KB)