I think a bigger concern than accuracy for bows is the total lack of deviation (or "bloom"), they're far too consistent.
Provided I don't move my mouse I can drop an arrow in the exact same spot every single time even at extreme ranges.
That is only doable with modern bows and arrows that have been machined with identical weights (and a lot of experience) etc.
Medieval arrows, whilst good, would not all have had identical mass, and they'd have production flaws.
Arrows should have a more pronounced "deviation" statistic to represent this spread of shots, with higher tier arrows having better (more consistent) stats, as they're presumably better made, whilst lower tier ones should land outside the target more.
I'm also not sure if the AI even adheres to all the mechanics the player does I've seen them fire with aimbot-levels of precision clean across a battlefield and get headshots