As I mod the game I find little things where lack of communication between devs causes one error that leads to hundreds more.
The thing that bothers me the most about the game right now is the AI. It is annoying to test each faction and put thought and effort into a unit design, only to see the AI pump out 100 spear maidens that I can kill with some advanced archers without taking a single hit. Why is this happening? It is a complex issue. One dev made the wage cost from labor way too high to start. This meant that a unit with better gear and good traits costs double what a traitless spearman costs. Since it is about 4 gildar per turn in wages, another dev made all the units in CoreUnits.xml use no traits. The idea was probably that these units would need to avoid too many traits in order to keep wages low. Since wages are back-breakingly oppressive, this would seem to be a good idea. The problem is that human players would much rather have a few very strong units that several weaker ones. We find ways to prevent our units from taking much damage, while the AI loses every battle from turn one. Our units level up and gain tons of Hit Points. They make new units at level 1. The game spirals into a pwnfest after that.
The next problem is that the AI Defs file uses the core units as a base to judge unit quality. There is a huge error here as it estimates how much labor and resources make up a cheap, decent, good, or elite unit. The definitions are way too conservative. It thinks a scout is a cheap unit, thus we see armies full of scouts. It thinks a Spear Maiden is a decent unit, thus we see 100 of them in the midgame when the AI is told to build decent units. The AI almost never gets beyond this point, unless you sit and wait for 300 turns while they get all the techs unlocked and cover the whole map, which I have done. Even then, they still have all those early game units floating around because you cannot upgrade effectively and the AI does not disband crap units.
My hypothesis was that this was the primary factor affecting the lameness of AI units. I modded the files to allow almost infinite materials at all levels and various amounts of resources. Then I deleted the terrible units found in CoreUnits.xml and made my own units to replace them. These units use all 3 traits. There is a new unit for each tech. The results were quite positive. My battle win ratio went from 1000:0 to 3:1. I also found that the AI was able to upgrade my designs in some cases. Apprentice Axemen were seen holding Boreal Blades. I did not design them that way, so the AI must be capable of refitting units as the AI Defs tell them they can spend more resources. I would call on the devs to rebalance the AI Defs, Core Units, Labor for Traits, and the amount of wages caused from Labor. It will get us one step closer to a competent AI, without which it is hard to balance the game.