Aion seems nervous because of the ship immediately sending Genai and Viede to deal with it. I wonder why he let Chrno come, he could have not left the teleporter and he could have killed them and he could have not invited them. But he did. He's even challenging Chrno to a race to the center of pandaemonium. He must have something else up his sleeve right, a use for Chrno? I wonder what that is.
With pandaemoniums 'chains' broken or shut down it seems the demons went out of control and multiplied. We were taught she was like the queen bee in the past so without her control over everyone they're going wild.
The line about Rosette not knowing when her last seal releases will be was telling. I didn't think of it that way, but when you've dedicated that much of your life force to fighting it seems clear it'd be a motivator to risk your life like this.