@ Ero I wrote this before, and here it is again: Each and every JCM costs possible content creators/vendors.

Especially if these JCM's are in the figure to correct a rigging error.

it is far better to spend a few days on proper weight-bulge map paintings, then to add a JCM.

And you can add muscle movements in the bulge maps too, no JCM's required for those either.

And if you don't get there? Adapt the obj file to get there.

But, I know, this takes time, lots of time.

Remember; All solutions are better then to add rigging correcting JCM's. All of them.