I just binged this whole series so far and quite enjoyed it. It's endearing, much more so than I expected after the first chapter. Lovely stuff.
One thing, however: I don't really understand the point of making her the reincarnation of someone from another world. I feel like Estelle's character could have been written almost identically with that element cut from the story. It could still prove more relevant later on, I guess, but so far it doesn't seem to me to add much of real substance to the series.
(And any suggestions that a peasant child wouldn't be interested in reading or learning vastly underestimates children's natural curiosity. The most desperately poor children in the world still show an interest in learning when given half a chance.)