At least speculatively, there is a high chance that some changes will be applied to the two civs at one point. Here are my takes of potential changes:
I suggest elite coustillier charge bonus reduced by 4x, but recharge becomes 4x as fast (i.e. 10 seconds). I find the average damage acceptable, but currently they kill certain units such as villagers and monks in 1 strike which I find unreasonable.
Though I am against pierce armor decrease, as Burgundians already have awkward enough options against archers.
Nevertheless, I think a straight-out nerf to the non-elite coustillier is justified. Burgundians already have a formidable power spike in castle age with cavalier.
I suggest making Serjeants only available in castle age, but start with castle age stats obviously. On the other hand, make Donjons cost the same as towers (50w, 125s) and possibly buff feudal age hp.
Currently the civ feels too one dimensional, but my biggest problem is that it makes them annoying to play against, whether you win or lose, while keeping everyone in feudal age. The current design maximizes annoyance rather than making them powerful imo. With the proposal, they should still be incentivized to build these straight-out buffed towers in feudal age that also becomes military buildings in castle age.
Thanks for reading.