Perhaps it's more of a comprehension thing. Things that happen that can't be understood from a 'mortal' POV are classified as magic. It doesn't mean that no explanation exists so much as it means that we just can't understand it. Maybe that's one of the things that's leading Kat to eventually becoming a god - she's learning more and more about 'magic' and learning more and more how to do things that others don't understand. If the ether is part of a higher plane and she's able to reach 'up' to that higher plane to force it to have effects back 'down' in the normal plane that's pretty intense.