Your starting surface have 3 different “densities”/parametrization inside.
That make you have “ripples” in that surface alone:
Anyway, this is with 3 simple c# scripts: (shrink, extend, blend)
(the blend one comes from another user from the forum but i cannot remember who…)
Ripple Issue_re.gh (88.9 KB)
This could be a solution, if the surfaces were ok to begin with…