Whenever I'm reading isekai with a theme like this, I nonetheless keep thinking the MC should be preparing for a catastrophe. Instead of spending all of her money on the doll, she should be investing it, preferably in businesses not directly related to her family, so that if she's banished or something happens to the ducal family itself, her investment would remain valid. And certainly she should find a way to learn the most powerful magic available at all, plus take care of her fitness. If there's any chance whatsoever to learn martial arts, even the very basics of sworsmapship, she should do her utmost to be taught.
Perhaps this will be pure aristocracy drama where she will never need any preparations, let alone fighting capability, but it would be cool if it wasn't.