The thing is that it is a bit too much. He inferred the whole fundamental principle of a revolutionary for the time system of accounting made by one of the experts of the field, how it works instantly realized its utility and why it is beneficial and all from a cursory look at an unexplained example written in a code made to make the whole thing unintelligible.
I raise this point for two reasons, first that this implies that Ryuunosuke is not only smart, not only smarter than most in the whole country but a veritable genius to crack Hana's code and from a few character be able to deduce what lies before his eyes and understand its benefits. And secondly, I feel like Ryuunosuke's insight steals value from Hana's accomplishment. This is something she has worked for near her entire life as a dedicated economist, and Ryuu, who is a general scholar with no mentioned specialty in economics or management, was able to get the insight as to how it all works from a cursory glance. Even if he recognizes the worth of her discovery, by saying 'why didn't I think it first?' he is undervaluing her accomplishments and the expertise she may bring to the table for him.
Now please, don't take this the wrong way. This is no serious matter nor do I intend to sound preachy or to chastise, however, if I bother a player of mine with a comment of this nature and ask them to change something, I wish them to understand WHY I'm asking it of them.
