"Over the back" is what we usually refer to as "coachspeak." You just proved our point.
Certainly a player can foul from behind on a rebound. But the foul is for pushing, not fo being "over the back." "Over the back" is not found in the rulebook. Neither is "reaching" but that's another conversation.
There's nothing illegal about a player jumping from behind and grabbing a rebound over an opponent, as long as the opponent isn't dislodged or pushed. Even if there's contact, it's not a foul if both players stay within their vertical plane. Sometimes there is enough contact to call a foul but if the rebounder is still able to rebound the ball and is not placed at a disadvantage, then we do not call a foul.
That hope that helps