Lol Pinkie wouldn't be taken away by the FBI,remember she can do w/e she feels like,hell shed throw the FBI a party!
Don't cry,Pinkie coming to our world would be nothing but joy.
(and pink explosions lol)
How do you know that the reason she was training with Rainbow Dash in part 1 of Princess Twilight was to fix these issues you speak of?
Whether she used magic as a boost is besides the point,she did what she did,which was a Sonic Rainboom equivilant. It has been confirmed because we see it and its blatant similarities to the Sonic Rainboom and just because the show din't have a pony screaming that fact at us or care to mention it again beyond that episode doesn't mean it din't happen lol