Well, you gotta know what not to do before you can do what you gotta. In theory he works, I don't have proper string in him so he doesn't hold together, but otherwise I think I can save his head, hands, and feet. The rest just doesn't work out but it will be far easier to make the next one.
The big thing is the mold builder, the light clay, shouldn't have been used at all but I didn't realize it wasn't regular clay until after it was baked and by then taking it off would have done more damage. My polymer skills need more practice as my biggest problem is it being too thin and cracking. Some of it is working this small as my air dry dolls have been on the larger end of the MSD scale.
Yoshida style engineering can work this small, he's 1/6, you just need to do as much as you can while it's uncured and not count on being able to file and sand the forms too much. I think doing the balls of the joints in the initial sculpting would do best, it's far easier to hollow out and refine the socket end.