If a player plays a shot that causes a ball to enter a pocket and jump out, without making contact with a cushion, then no penalty for failing to hut a cushion will apply. For the purposes of the Legal Shot rule (determining if a ball has hit a cushion), the back of the pocket will count as a cushion. 

If a player plays into a ball touching a cushion, and that ball comes away from the cushion and returns to the same cushion, without touching another object ball, then the shot is a foul. 

However, if that ball comes away from the cushion, hits another object ball, and returns to the original cushion, then the shot is legal. 

Simultaneous initial contact between a 'ball on', and a 'ball not on', is NOT a foul.

If a player plays into a ball touching a cushion and the cue ball simultaneously contacts the 'ball on' and the cushion, a legal shot has NOT been completed.