The barrier did indeed try to regenerate and increase the protection in the area where Roan was using his Dark Element. This was the same barrier that stopped several Divinity Realm experts who didn't have their cultivations suppressed last time. So, you would imagine Roan couldn't possibly break it with his Transition Realm at the moment. There was a difference, though. Roan wasn't attacking from inside, which was what the barrier had been designed to protect against. He was doing it from the outside, corrupting it.
The barrier still tried to regenerate itself with difficulty, especially since it was very, very old. Chances were, it had already lost quite some of its power.
