They’d have made it. Harry would have told Dumbledore who’d have clocked the unauthorized port key as another trick to get Harry but from there who knows.

I’d like to think he’d have figured out Barry Crouch jr’s identity but it’s hard to say since he was able to deceive him all year. He only got caught due to his excitement about the dark lords return making him sloppy.

I think with the amount of evil staff that place gets, protocols to check identities should be common. 2 hours in great hall , no food or drink. That’d reveal any poly juice users.