If Madeleine was in that bag then she definitely wasn’t in Smaithman’s arms so I don’t think most sceptics will go along with your hypothesis. I certainly don’t because a) what bag b) what were its dimensions c) no one invites people to look for a child in their apartment that is lying dead in a bag in the wardrobe unless they are stark staring bonkers.
You are at least trying to understand the Prank Theory. I have never said it is Madeleine in the bag. Remember in my theory she wakes and wanders and then gets taken away.
So in my the theory Madeleine is not in the bag, but someone else is, the driver of the child replacement. There is this unknown child in the bag. So someone must know the deceased child is in the apartment, but we don't know who and I suspect it wasn't Kate.
But then the deceased child goes missing from the apartment, possibly after the PJ have locked up for the night. Who removed it, I wouldn't like to guess, but if the rooms were locked they'd need a key.
So in my theory there is plenty of time for cadaver odour to develop, but cadaver odour is species specific, and not identifiable to a specific person. Human cadaver odour, located in 5A, does not imply it came from Madeleine.