So have you dealt with teppojutsu as a GM?
I did a campaign once where the almighty Iweko ended up secretly preparing teppo legions to repel the Yodotai invasion. It lead to the installation of a harsh dictatorship that removed much of the samurai privileges and redistributed the lands ( a la Tokugawa sword hunt). My players had to take a part in this. Lead to epic and emotional moments where they had to accept the "breaking" of rokugani culture in service of the god Empress.
The taboo on firearms is heavy in Rokugan, but a Samurai should serve his lord with any reasonable and efficient weapon.
In Japan history, teppo definitely played a role in the rise to power of the three great unifiers.
Even Seven Samurai has teppo. Imagine what Crab could achieve with artillery and Teppo.