No problem.I don't know. We have a few modders here though. Hopefully they won't get spicy if I tag them.
Easiest way would be to just reduce accuracy of all bows in spitems.Do you know if there is a way to reduce base accuracy for all archers?
Otherwise you can use dnSpy or something like it to edit the dlls/make a mod.
To reduce Ai accuracy you can edit the method SetAiReleatedProperties (either directly edit the dll or use harmony to add a postfix to the method) in the class AgentStatCalculateModel in Taleworlds.MountAndBlade.dll. The last properties AiRanger(Lead/Vertical/Horizontal)Error probably directly impact Ai accuracy so just reducing/increasing them should work.
Or to reduce everyone's(including player's) accuracy you can modify the method UpdateHumanStats (either directly edit the dll or use harmony to add a postfix to the method) in the class SandboxAgentStatCalculateModel in SandBox.dll. Reduce/increase all the accuracy related properties in agentDrivenProperties.