I agree that the Koreans in game is heavily gunpowder-oriented.
As a Korean, I can say that the Koreans in game don’t need the Fire Lancers. Historically, Koreans during the Joseon Dynasty which is the main theme in game were more for Hand Cannoneers. All other gunpowder units are okay considering history, but Fire Lancers? Historically not that proper.
If we need to remove some other gunpowder units from the Koreans in game, let me say the Bombard Towers. They’re very expensive and the Koreans already have their unique technology, Eupseong, which increases the range of Watch Tower line, and that’s much useful and effective. Bombard Towers are just no more than a wasted building. Of course, they can be quite dangerous in late games, but most players would rather choose Heavy Rocket Carts with Shinkichon upgrade than the luxury towers. Anti-Bombard Tower units are only Siege Weapons, which are easily removed by Rocket Carts anyway. No need to use Bombard Towers for the Korean civ.
Thus, I want to say that the Koreans in game don’t need the Fire Lancers and Bombard Towers.
Turtle Ships, Hand Cannoneers, Rocket Carts, Bombard Cannons, and Cannon Galleons are enough considering both the game and real history. If we were to remove even one more, I’d choose the Bombard Cannons. Instead, the Koreans should’ve been more Archery-oriented including the Cavalry Archer line.
The Chinese in game should absolutely be more gunpowder unit-oriented.