As I was writing the explanation of this issue I figured out the solution, so it’ll be resolved after this comment. Basically, some paths were defined in clockwise order, and others counterclockwise, depending on how I traced them in Inkscape. This caused problems when trying to use them as clipping paths. The solution was to use paper.PathItem.reorient(clockwise=true) whenever encountering a shape defined in counterclockwise order.
As I was writing the explanation of this issue I figured out the solution, so it’ll be resolved after this comment. Basically, some paths were defined in clockwise order, and others counterclockwise, depending on how I traced them in Inkscape. This caused problems when trying to use them as clipping paths. The solution was to use
paper.PathItem.reorient(clockwise=true)whenever encountering a shape defined in counterclockwise order.