Thanks! Yeah, this is a good suggestion. All houses were supposed to be interactable, but due to the time limit, I wasn't able to update the game with the content I had planned.
In fact, there were many more houses, characters and costumes (some are in the cover art, for example) already designed and planned, but my wife got sick the day before the deadline and I ended up having less time than expected to complete the game... but she is fine now. :-)
Try talking to the same houses with different costumes. The idea is that the normal sweets would be given to anyone at the door, but the special ones, only for those wearing their favorite costume.