Couldn't you just leave the area (like go to another map like Hinterlands, or back to base) and come back? I would assume that would reset any magical effects in the area. Maybe don't bring Dorian next time?
You'd have to re-cover the ground, but at least keep all your other quest progress.
Unfortunately, the barrier didn't disappear even when switching areas completely. I can no longer target it so it's impossible to destroy a second time. My completionist OCD is going off bad, might just have to bite the bullet and reload from an earlier save.
