The name for a "paper money collector" was mentioned by Robert Leuver, the former head of the BEP (Bureau of Engraving and Printing) in a David Lisot CoinTelevision video at minute-mark 6:16 It wasn't "numismatist" or "notaphilist," either. It was something like "singraphist(?)" Am I hearing that right? Can you catch it? Take a look and let me know, if you can figure it out!
The only term I’m familiar with is Notaphilist. That is the definition of a paper money or collector of Notes.
Read a bit here. Syngraphics https://www.numismaticnews.net/community/paper-money-collectors-lack-identity
Nailed it! Thank you, @alurid ! Syngraphics. So the person who "does" syngraphics is a syngraphist, I guess.
If you watch the interview, you'll notice how in 1986 Robert Leuver was saying that the BEP was NOT keeping up with the counterfeiters! Another revealing interview...