After getting my stone unsealed, on the way back to school, I decided to stop by the item shop to see what the damage was - Arche did, after all, apparently disobey orders completely.
Apart from a total lack of reaction from dad, I also found that the game mostly freezes (UI goes away, all input stops working, but animations still play) if I try to talk to mom while unisoned. I wanted to show her why I'm not at school, see..
Fortunately I didn't lose more than five minutes' running.
If you get it fixed, I'd like to know if there's supposed to be any dialogue attached to this event, so I can go back and see it.