From how I understand it, he's back in your world. I'm not sure if you were told, but the concept of our worlds being destroyed is completely false. People have disappeared and returned with full memories of their previous time here. However, an instance like this, where a name still remains on the network, means that the disappearance is temporary.

[ yeah, he doesn't really get it either. he had plenty of questions for athena when she explained it, so he's just rewording what she said about it. ]

However, the flow of time between Cerealia and our worlds has discrepancies - what will be three days for us here could be any possible length of time for him in your world. When he returns, he may have some new memories of events that took place there. Unfortunately, there is no way to speed up the process on our end.