At first, when Isabel saw Queen Sofia, she felt genuinely happy from the bottom of her heart.
It wasn't some utilitarian thought like, "I can get through this ceremony easily"… it was simply the feeling of being very fortunate to have the opportunity to see her grandmother who had passed away once again. It was like the joy one feels when seeing an old friend or classmate featured in the newspaper.
Moreover, Isabel noticed that the introductory plot mentioned it was "the proclamation of Avalon's kingdom's destruction," and that it would happen in the near future. Therefore, it had some reference value… As the Queen of Avalon, she had to take this promotion ceremony very seriously no matter what.
Maybe she could obtain some information from it to help the true Avalon avoid this future.
But soon, Isabel saw her own cowardly and weak appearance.