Pretty sure Han was called a General in ROTJ. And why would Rey not know the name of the guy who helped defeat the Empire in the battle of Endor? It’s history.
Does the film actually say she doesn’t know Han fought in the rebellion? She is just way more impressed with his smuggling/piloting fame/infamy in the scene where they meet…
Rey: This is the Millennium Falcon. You’re Han Solo!
Han: I used to be
Finn: Han Solo the Rebellion General?
Rey: No…The smuggler.
Finn: Wasn’t he a war hero?
Rey: This is the ship that made the Kessel Run in 14 parsecs.