Geometry.DistanceTo is giving you the wrong list structure for your surface UVs. Use list levels instead. You’re also using the values from all your locations rather than the minimums when you map your values and get the colors.
It’s not perfect yet, but it’s a lot closer.
And just FYI, I usually find it easier to use the points themselves rather than trying to map to a surface because you can just flatten the list of points and ignore any list structure or order.
