It seems Valiant missed your question. Really, the reason they aren’t included is probably because when whoever it was added them, they either decided not to or forgot to put the spawns in hardware stores. I have no idea which, though I see no reason they shouldn’t be included.
In regards to breaking things, placing the spawns in the standard hardware store spawns will just make them spawn in the old hardware stores as well, but if you’re making a new spawn list with the paint cans in it, then it won’t affect anything but your new stores.