Yeah the pipe corrosion is he big thing. And if it corrodes pipe and liners, no telling what it would do to the baffle in a EPA cert stove.
baffle and secondary tubes etc would be a concern.
My owner's manual says not to burn corn, coal, saltwater driftwood, treated lumber, kiln-dried dimensional lumber, etc., so I don't. Surprising what you can learn from an owner's manual!
I don't have a cat stove and my owners manual does not mention anything about coal. I have read the manual cover to cover several times. It says not to burn salt drift wood and cautions about the potential for overfiring the stove by burning mill ends, but does not mention coal.