The division of units into infantry/artillery/cavalry seems pointless
I don't really see the point of having three different unit types to then build the same 50/50 army every time. This system is neither engaging (no thought goes into it except 50/50 if you can afford it). It is not realistic either because no army was ever made of 50/50 infantry and artillery. Moreover, cavalry could actually be 100% of the army. It even creates weird cases in which if you want to turn some infantry in artillery regiments, you have to delete and rebuild barracks
In EU4 this tripartite division made sense because budget costraints were much stronger, tech advancement made the optimal composition change (battle width increasing, artillery being getting the second pip) and national ideas changed the optimal amount of cavalry.
For the objective of victoria 3, i think it would make more sense to have just a generic infantry regiment with an artillery slider, which increases regiment size and offence but slows it down and increases supply requirement.