On that wall right next to the two chairs. They could've incorporated the existing neon-light border except have the
entire wall one big neon light, that changes colour a la BB8, i.e. green for an open door, red for in use, blue for not in use etc.
That way the Diary Room would've
finally moved, and the stairs leading into the house could've been covered up again.
I honestly think it's the only thing that's letting this house down.