Impressive. We would like to isolate the box path for a particular bad spline, like this example: Pointy edges in places where straight edges fit
I think showboxes here is rendering the box space actually used, after splines have been calculated and unused space has been recovered for potential use in other splines. The documentation says we can use showboxes=1 for pre-route boxes and showboxes=2 for post-route boxes. Does this still work?