Some mercenary companies in Crusaders Kings 3 should come with siege weaponry.
Siege engines would help them take and defend castles faster and easier, and give them an advantage in battles. Many historical mercenary groups were skilled in siege warfare and had access to siege weapons. I made a post in Discussion regarding this topic with much more detail so feel free to take a look.

Is this making the mercenary companies smaller? I installed a few days ago and all the companies now seems to be 250-ish in size? They have the right number of knights but suffer from the game problem that if I have 20 mercenary companies it's incredibly difficult to move them as a single unit rather than 20 individual units of 250 mercs. It's a dumb tooltip thing where hovering over the combined companies let's you pick an indiviual unit, but doesn't let you move the whole group. Makes it difficult to engage in running battles when I have to point and click to send 20 tiny units to the fray.

it cant be done with how CAP innovations work, if he changes it, then sure

Sorry, I meant would it be able to make the cultural MAA match with the mercenaries culture? Or is that impossible modding wise?

@eoinraffs this mod does currently, but due to how the innovations work in CAP, sometimes the men at arms and cultures do not match, giving the wrong cultural unit for certain cultures.

Hey, would you be able to do a patch with cultural armies pack to use cultural MAA as mercenaries?