You are welcome.

Just make a little experiment to stop scratching your head:

1) Place a looping string under the wings (just like the Vanessa) and hang the model horizontally.
2) Place an arbitrary weight on the tail or the nose.
3) Watch the model swing away from the end on which you placed the weight.

If it happens that way, it means the model is dropping the end with the added weight, as it should be, and also that a properly built Vanessa rig will solve the mystery.

I believe that the problem you have is related to the natural instability of the situation where the CG is above the pivot point (skin of the wing in contact with the balancer).

As the schematic shows, the situation in which the CG hangs from a pivot (Vanessa), is self-stable.

Regards