I could see it spiraling or even curving, but it still seems highly unlikely that it would turn around 180, pass by a point where it previously flew over, and cause that much damage after passing through a concrete wall. "back towards" implies just that.
Frisbees and boomerangs in flight can certainly turn around way more than 180°. Or with sufficient wind, any projectile can turn 180° and come back the way it came.
I'd doubt a spinning cannonball would actually manage that, but it probably only takes a curve of 90° or even just 45° for some sensationalist journalist to exaggerate that into "spiraling back".
There was a recent analysis of soccer shots that seem to curve quite considerably, and it was deduced that the soccer ball in flight would actually form a spiral on to a point. Only that the ball hit the net or the ground did it stop its spiral trajectory.
