Again for the trivias about mile's (mis)adventures about being (a)normal, now the turn of mavis
she "cannot" do magic normally because an hereditary problem where she can't send her mental thoughs to nanomachines outside her body (think in a broken antennae) BUT she can inside her body, the sending problem was resolved putting nanos in her sword, allowing her do "ki" (aka magic) tecniques
I think a more accurate ending would have been failing to stop the !not-Mile monster and everyone in the world getting turned into a catgirl. Like I believe she would actually stop.