When Jade brought everything from the B1 session through the fourth wall, how come she seemed to have left Prospit and Derse behind? I guess Prospit was mostly destroyed by Jack, but B1 Derse was still perfectly intact, right? Did she just leave all the black pawn carapacians to die in the scratch even though they hadn't done anything wrong?

Well, the Dersites don’t agree with the end goal of the game anyway so bringing them along wouldn’t have done any good.