The script has only been tested and known to work for sure with the default human made character in FuseCC rigged with the Mixamo service.
Any other character types will depend on the bone hierarchy they end up with. If they have the same bones as the default rigged characters then the script will work.
You will need to ensure the character is symmetrical with same pose and size for limbs on both sides.
Mixamo Rigging Options need to be:
Skeleton LOD: Standard Skeleton (65)
Facial Blendshapes: Disabled