The Hinge and PlasticHinge goals work on sets of 4 points like this:
In your definition there are different numbers of points going into these inputs, so they aren’t in matching sets of 4.
Generally I would not recommend trying to find these points manually by shifting lists and so on as is happening in your definition, since you can’t usually rely on the ordering of the vertices.
Instead, use the
HingePoints component (found under the Kangaroo Mesh tab). This extracts this set of 4 points for every internal edge in your mesh.