I am telling you what the images should look like when you are done with the hand comp, I wasn’t really outlining layer order, you should be able to figure that out by adjusting your comp until it looks like the image here, which I just photoshopped to illustrate.
You need to precomp the solid and the hand roto layer together, then you can apply Mocha Pro on the precomp. Precomping everything and moving all the attributes into the new comp is how you get around any trickyness in AE.
No need to overcomplicate this, it’s just cutting pixels out with transparency, and whatever pixels are in the transparency will be the color of the original plate if you don’t replace them with something else. This is just replacing those original pixels with a medium skin tone color of the hand. It’s less a Mocha fix and more a compositing fix. This works for objects with depth of field transparency, and any feathered or blurred edge. I can’t really walk you through the exact steps because I can’t see your shot, but conceptually, you’re looking to replace BG plate pixels with new information and adjust until you’re happy with the results.
In Nuke this is wrapped into an Edge Extend node and of course you still need non motion blurred roto on top of that node as well.
In Flame it is called Pixel Spread and you still have to composite over it.
In AE, some artists do this with Boris FX Sapphire tools S_Distort and composite over that.
Or you can precomp over a color. There’s a million ways to do this, but the basic concept is you need similarly colored pixels for the motion blur roto.
Some people tile the texture and use the wrap edges option. Some people blur the cutout hand and composite it over itself until it is not feathered anymore, but opaque, then reapply the motion blurred matte on top of that. There’s so many ways to composite and there’s no “right way” there’s just the way that works for your shot.