Dialog
Rinzei: With the airships connecting Jeuno with the three nations, the flow of goods has become much more consistent. Nowadays, everything comes through Jeuno!
Of course, Jeuno is situated smack-dab in the middle of the three, so this town was destined to grow and prosper.
I think the airships are a subtle form of pressure on the other three nations. That way, Jeuno can maintain the current balance of power.
Nobody would want to upset the masters of such advanced technology, would they? Nope, can't blame Jeuno for keeping the secrets of airship-building to itself.