Those 2 things I think I understand same way as you say. I'm not familiar with XiangQi Cannon. But the sentence "Units the Reaper moves through do not block movement for 5 turns" is maybe the problem. I understand they become "ghostly" from Reaper only after Reaper moves through them. But for Reaper to be able to move through them, something must have made them (or they already are themselves) "ghostly" before. In other words, Reaper does not prepare them for himself before the move to move through. If he could jump over for the path attack (e.g. like frog) than he would not need them "ghostly" for himself, and he will just make them ghostly after he jumps over.