I say Schala can cross dimensions because, like, you know, in the ending she's on a different planet, which is quite possibly in another dimension. Le Gasp. And the fact that clocks go all wonky when she passes them is surely symbolic of her ability to wonk up time/space. That was a heavy indication. And the fact that she's able to decipher the meaning of the life usually implies sainthood/godhood/Buddah...hood etc., so added to the fact that she can say, without any sort of reasoning to think so, that time will rejoin and Serge will have no memory of adventure and still be completely and totally right, should mean something right there.