It does look like machine! The cuts should look Much better.
Peter, I'm totally guessing, but you have basically 2 different materials. Maybe 2 toolpaths for the same bit? One pass at your dialed in speed and feed for the full depth (plus a hair) of the top layer, and then a second pass to your full depth(at THOSE best feeds and speeds for the bottom material).
But first figure out what is loose on machine and make sure material isn't moving at ALL.
Like I said Guessing what I would do, if I were trying it. I might even try an offset of .01" on the top layer so the second toolpath would just have to remove a skin and bit deflection would greatly lessen.
I could be ALL wrong because it's plastic.
scott P.
2013 Desktop/spindle/VCP 11.5**
Maine