Awesome! If you find any issues or have any suggestions, please do not hesitate to let me know!
For the bones twisting, the latest update might fix this as well, as now it uses the bone's initial/resting forward position, rather than a hard-coded Vector3.UP. That said, I'm not totally sure that will fix it. I'll try to see if I can get a test rig hooked up and will test it. If it doesn't fix the issue, I certainly don't mind adding a "use_target_up" option if it would help.