Amelia was sickly before the curse was fully in effect

The fairy tale of Vanitas may be relevant later

This could be foreshadowing

Naenia took Amelia's true name after she was cursed?

Vanitas is not holding the book in the moment he saves Noé from Amelia but the visible world formula around him implies he used a similar power. He seems to have used his left hand (his unmarked hand) interestingly

There looks to be a crack in the astermite on the Book's cover

How did they survive?

Whatever Vanitas is talking about here: