I think that the narrator, as hilarious as they are, are undermining Mia's actions in this chapter. The only thing that Mia misunderstood was the other princess' intentions, thinking that it was a form of advertisement instead of a silly prank.
She knew of the Empire's future problems, identified a way to solve them while improving their relationship with a country with a mayor role in the future, and immediately took action to accomplish it.
So, even if she didn't have such a deep insight a Ludwig believes, her intentions, knowledge, efforts and foresight are still completely praiseworthy.