Asians can already spend generic resources in Castles to train units with some Western-style artillery roles. For example, Hand Mortars are the Chinese Culverin-like units, and Flaming Arrows are the Japanese Falconets-like units. The Asians do not need to have access to other types of artillery with generic resources. Want other types of artillery, spend exports, that is how the Asians are designed in the game.
I came up with almost the same idea quite a while ago.
In my blueprint, the European allies provide the same type of artillery that they include in their expeditionary armies. So essentially buying artillery alone without buying more of the other types of units in the armies.
This infinite shipment button will be in the fourth column of the third row (the location of Meiji Restoration and the Livestock Pen Wagon shipment). The Dutch ally should also remove the Livestock Pen Wagon shipment so that the Japanese can train the sacred animals of their traditional religion at Shrines instead of relying on foreigners. Since Russian ally will still provide a Factory, there is no need to worry about not being able to purchase Heavy Cannons if Chinese Isolation replaces the German allies.
Meanwhile, this mechanic can work together with some new artillery shipment cards in the pattern of Mysore Rockets, for example providing Falconets and Heavy Cannons to Chinese by the name of Hongyipao and Great General Cannon. But in any case, I insist that these artillery cannot be directly purchased in buildings like Castles or Artillery Foundries fully with generic resources like coin, otherwise it will break the balance, especially in the later stage.
The correct spelling is Kunikuzushi (国崩し, “Destroyer of Provinces”). It was a Portuguese breech-loaded gun imported from Goa, same type as the “Folangji guns” in China, not produced by the Asians themselves.
Another term, Ozutsu, was for guns produced by the Japanese themselves, but I would have preferred this to be used to replace Morutaru’s name, especially Morutaru’s skin is quite close to some types of Ozutsu. (Although the Ozutsu in AoE4 is directly hold on hands rather than on a cart.)
I think Isolation should not provide artillery in order to be significantly different from European allies, and Japanese Isolation already has no button space.