This is my last resort in trying to figure this out.
I have a reverse pendulum swinging (an alien with an eyeball attached at the top of a stalk) and I would love to be able to have the eyeball react with inertial bounce. The stalk is anchored at the base. The eyeball's anchor point is attached directly to the stalk, and is parented to that layer.
I have found an inertial bounce script to aid in the bouncing of a rotation, but requires the position data of the non-anchored end of the stalk to drive that rotation.