Interesting , thou I think a line must be drawn somewhere into historical accuracy.
Lets say that as this game is company level 123 men per unit guns should reflect the exact amout of pieces and men as well, as scaled art vs real infantry will be unfair as well.
On the same line light infantry were the same size as line in most cases.What I mean is that same historically accurate data is not always viable.
Artillery shouldnt be the same for every nation , you are absolutley right, but maybe you could work something throu the stats to reflect these differences acordingly to historical data, instead of varying the amount of guns or crew.
Because probably an 8 piece spanish battery was cheaper than a 5 piece brtitish one , just because bronze was more available in the peninsula, french would say that their guns should be cheaper as they had more loot from the prussian army, and some may say that a battle is fought in 1814 so the french have no guns at all. And arguments will be endless.
A standard should be agreed that suits the game balance, so if you can compile all historical data and come out witha neat piece of artillery stats that represent closer the historical accuracy Iam sure the Lordz will be more prone to use it. And althought it may sound like a compromise , it will be a step fodward in the historical direction.
Can you do that ?