while I'm no expert
fake die celator or anything, a friend of mine engraves coin dies and banknote plates for the Royal Canadian
Mint. They use a powered chisel to do
fine engraving, which makes the
work a lot easier and faster. They don't need to use hammers and they only have to use manual graving chisels for specific precision tasks. Most of the
work is done with these powered
tools that vibrate a high speed steel (i.e. tool steel) cutting
bit back and forth, simulating the manual hammering of a tiny chisel to hog off metal.
These machines leave a uniformly spaced chisel appearance under magnification and top engravers then take a finishing cut with a manual graver to smooth out the bottom of lettering, for example.
Here's a couple pictures of the graving
tools I'm talking about from the 'net, noting they are specialty items costing many hundreds of dollars:
Professional engravers of coin dies would not be using any
type of rotary engraver like you might see at a
trophy plaque engraving
shop. They would use these small power chisels.
I suspect this is what Dr. Propokov was referring to, though I would not be expert enough to easily spot the difference between the spacing and uniformity of a machine chisel vs. a manual one that was hammered by an experienced ancient celator.