Those ages just have to be a some kind translation error, considering how both of them look or act, not to mention how weird a party like this is to someone aged ten. Young children of high standing were often held very close to chest outside of select circles. If you are aiming at something like a debutante with this, you are at least half a decade off. That aside, even outwardly, has the author actually seen a child? Interacted with one?
Not that I actually suspect a TL error, I'm just grasping at straws.