He can change at night, while he's asleep. I think these last few chapters are still supposed to be the same day. Those are probably the dishes from breakfast that they're doing in this chapter, so probably only a couple of hours since Baa-san woke up with no memories.
Hey now, those japanese colds are no joke! They'll have you bedridden and delirious with fever all day one day and totally fine the next! And it's always waiting to strike again whenever you get a little bit wet!
How small was her town that it didn't even have a grocery store? I've never been to a small town that didn't have its own grocery store and I've got relatives spread all over small towns across Kansas.
The placement of that wind-up key would prevent her from looking up. Also, those external joints would easily become clogged with dirt, or worse yet, pinch small fingers. Very poor design choices for a teaching robot.
So the alien thing was real? Or was the brain in a jar also part of her delusion, like the master being there already? How much of this manga is real and how much of it is purely in Kikimora's head?
Au contraire!
Could just be that the author doesn't have any more ideas for the main couple, so decided to wrap up the b plots real quick before the end.