I'm thinking we should just standardize it to "catapult." Onagers are catapults, in the broad sense. "Stone throwers" might be needlessly pedantic and "catapult" is a term most people understand. "Bolt shooters" though seems to be a good term for scorpions and oxybeles.
I still don't like that they're called Stone Throwers in some places and go by a different name in others (for example the arsenal, where you build them).
https://www.gov.mb.ca/sd/pubs/parks-protected-spaces/park_info/whiteshell_petro.pdf
https://en.wikipedia.org/wiki/Petroform
Could be a reference but their exact relationship with ancient Anishinabee (Or when they were built) is not clear.
Some are tentatively dated to 500 AD based on nearby archeological finds.
I like the new forge personally, i feel it's more accurate without the big chimney.
I'm not sure the wooden totems fit, as far as i know they were mainly used in the Northwest.
Well the idea is that the onager serves an area of effect role to target bundled up infantry. It will be only moderately effective against buildings, but its simple design compared to the ballista means it can be built in the field by legionaries.