Isn't it super obvious that a bestowal magic tool is very practical and can make the twin kingdoms stronger?
Like they can industrialize, make magical weapons, maybe try to invent powered vehicles???
FFS they havent thought about glass until fucking Zenjirou came?
Those obvious technological hindrances aside, the politics are pretty nice.
It would be strange if they didn't know about glass at all. That goes back thousands of years on Earth and was basically the plastic analog of the Roman empire. It's not weird that they didn't realize you could make optical-quality glass spheres, though.
We didn't know how to reliably make transparent glass until the fifteenth century. We got to where we could make small pieces of clear glass that were good enough for optical purposes, but we couldn't make distortion-free glass panes until the mid twentieth century. They're hard to find these days, but if you can find a house from the 1940s or earlier with its original windows, look closely and you'll see the light's all wavy through them. You might even see where the glassblower's pipe was attached - window panes were basically blown glass spun into wide, thin discs and cut square.
As far as everything else, industrialization is only obvious once you've seen it. They have a system where all the wealth is concentrated in the aristocracy. Commoners grow or make most of what they need, and communities are largely self-sufficient. Complex items are one-offs made by artisans. Without a sizable middle class to buy manufactured goods, industrialization doesn't make a lot of sense.
You also need a decent scientific understanding to start industrialization. Even if the Romans had seen the benefits of industrialization - which they didn't for the reasons mentioned above - they couldn't have built a steam locomotive no matter how much money they threw at it because the science simply wasn't there.
