In a&a 1942 2nd edition, can bombers conducting a strategic bombing raid and fighter escorts retreat?
You are 100% correct. Retreating is part of general combat, Strategic bombing is a special type of attack that has no concept of retreating.

AA units only get one shot at the inbound bombers, so unless you changed your mind about the bombers actually carrying out the attack, retreating has no meaning with respect to strategic bombing.