Bella watches the house come together for a bit, then wanders back to the palace to see if Fëanáro is still in an inventive fugue state. ...She might need a hobby less mercurial than tagging along with a toddler and less resource-limited than experimenting on magic. Learning Quenya can be it for the time being.
She sits by him and practices Quenya and studies the vocabulary she has so far.
Bella's not great at rote memorization so she can occupy herself drilling on what she already has without needing a new batch of words for a while.
She goes back to Lórien. Maybe Olórin would be entertained to teach her Quenya.
That is probably plenty of Quenya experiences for her purposes. Hey look it's an alphabet!
She writes down sentence patterns and more vocabulary, handwriting in Quenya gradually speeding up as she remembers how vowels work more reliably.
Zzzzz.
Well, then Bella can teach him a new spell! Arcane mark? Increased character limit arcane mark? Dancing lights? ...That one's not really useful here. He could also try one of the bigger spells, although he'll be able to fit fewer of those in per sleep.
All right, she has to make a new scroll for that one since he doesn't know regular arcane mark such that she can just describe the revision. He can watch.