Would it be accurate to say that the final product will be injection-molded plastic, mastered off the original digital files, rather than off of the physical prototypes?
I would assume this is the case, several companies now use CAD to sculpt their new miniatures. As the Mech's are plastic I would suspect the metal moulds are machined using the original CAD as the old method for making moulds thank I know off was to produce 3 ups and cut the moulds using those.
If the Mech’s were resin or metal, then it’s possible the moulds would be made from printed masters. Forge World has had a few resin models show the steps, I haven’t seen examples. While Corvus Belli use metal and I think they produce printed masters, but they don’t have the steps showing, they might use a milling machine rather than a printer to produce them.