what you describe is quite possable.removing mods above the North would require starting a new game. TOM might know more on that. 1 thing you can do if it is crashing at the same time is save and play,save and play. try to get a save point right before the crash. then you can check the building construction to see if the iron fittings are being placed at that moment.
from what i remember, there is a difference with honey and/or sugar between KID’s formats and TOM’s. can’t remmember if it causes a crash or if the workplaces just won’t use the other’s items.