I should learn not to read your stuff before I finish my coffee, because my head immediately rabbitholed down "how would an antiquarian numismatist validate these coins and what effect would the strange temporally-shifted environment of the Red Devil mansion have on their characteristics"

I got as far as "well, there's been no widespread nuclear tests in this world, I don't think, so the real-world validation method to prove they existed prior to 1945 won't work" before I could stop myself XD

Seriously, tho, some collector is going to be very surprised XD