Hey eastriverlee!
I'm so sorry I did not reply until now! Itch.IO didn't send me any sort of notification, and I haven't checked the Twisted IK 2 forums in several days.
It may be something unrelated to Godot with the bones and mesh getting out of sync, but I am not positive. Especially with 3D Joints, Godot's implementation can sometimes have issues with the joints floating or getting separated, so if you are using 3D physics joints that may be contributing to the issue.
I'm super glad you were able to find a solution! As for the solution you found, its very similar to the one I implemented in the upcoming version 2.4.0, which will be released on May 8th. Your code handles angular velocity slightly differently than mine, so I am curious to see if it will do better, as my implementation still has a bit of sync issues that I couldn't quite get rid of. I currently do not have any hints/ideas on improvements, but I if any come to mind, I'll be sure to let you know!
Thanks for the reply and again, huge apologizes for the delay in replying!