The TE ROTJ helmet moulds are made from casts of the outside, not the inside. The replicas he made (and still makes) are far too soft in appearance comparing them to original LFL helmets.
Again, the eras are the main factor here. None of the screen used ROTJ helmets have the ANH/ESB ear caps, just the ESB Mk2's. I've never looked closely at Matt's original ROTJ helmet or your casting, so could you do a comparison of the decals to show where they differ?