Hello! I had this problem with my son, too, when he turned five months. No tricks here, sorry, my son even rolled out of the sleep positioners in his grobag. I think this is just one of those "suck it up and wait it out" situations.
Personally, I don't think it matters whether you flip him over or not, do whatever suits you. If you think he'll EW, why not flip him back? More important is to give him lots of rolling practice during the day so he'll be able to flip himself both ways.
Really soon it will pass, and he'll do what he did before.
It took about five nights of this, I think, before my son got the hang of going backwards and forwards. I flipped him when he was really stuck and calling, left him otherwise.