Again, I am clueless about Kangaroo and can’t use your code (I have Kangaroo2 installed), so this probably won’t help. There are some bizarre hacks here to adapt @DanielPiker’s AnchorXY.gh example from the Force density thread, and the results aren’t pretty. See the purple group, for example, which culls the “naked points” around the hole edges to prevent them from being considered “anchors” and includes them instead in the “clothed points” to be moved, constrained only in X and Y while “floating” in Z.
Kangaroo doesn’t always adapt to changes upstream, so to speak, such as changing the Max Edge length slider (Custom Mesh Settings) of the original mesh, or changing the number of holes. It flails horribly in those cases until I close and re-open the GH file, though it does respond as expected to changing the Z depth slider. Amusing but not that impressive.
By the way, I did try anchoring only the corner points so the edges could sag too, like the pavilion picture, but the result looked bad. My two cents worth from the Kangaroo peanut gallery.