They are not allowed, we state in the rules that runs can't be on everdrive or flashcarts, which is what repros are.

Flash carts allow you to download new games/use save states, repros aren't flash carts, they're homebrew versions of the original game. Also unless they alter the rom in some way, it's pretty much impossible to tell if someone is playing on a repro cart unless they pull it out of the console and show the camera, so I don't see why repros are a no-go

"Only officially released versions of the game are allowed for console runs."

I guess this means they are not allowed, whether they are flash carts or not. I guess you can't expect mods to check that every weird version doesn't give you an advantage. I understand that it must be frustrating to buy an original cartridge but for now they only cost 20$ (It still can be a lot I know but prices might go up down the line)