Now, to address the wrong headed notion of the flight characteristics you hold. Do you seriously believe human technology can duplicate 90 degree change of direction at eight thousand miles an hour? There is actual radar evidence of just such motion by these 'things'.
It is pretty common for cultures to scream “witchcraft” when they see something they don’t understand.
My thinking they are in some sort of plasma field that eliminates G forces, thus allowing those types of turns is as far on one end of the spectrum as your demons are on the other.