I was a bit confused about a thing whilst reading homestuck and was hoping you could help me understand!! when the scratch happened when the trolls/karkat was about to claim the ultimate reward, do they remember that happening? Or did basically all that get erased and the outcome was changed so that they were on the meteor, at that the outcome of them beating the game basically never happened?

The Scratch doesn’t affect the Troll Session in the slightest, they’re in another Universe entirely, a complete different continuity than that of the Kids. Bec Noir exiles himself to their Session, and they mistake this for the effects of the Scratch, but the Scratch itself NEVER does anything to the Trolls.