They usually detect the mob further beyond the range that their bow can reach, should set it to 8, similar to vanilla skeletons bow firing range
https://imgur.com/bC5Rt4D

Note to self: Lower this range, but try to make it detect enemies that are below and in front at a longer range to allow warriors sniping enemies from watchtowers.

Forge is no longer being supported, and the mod is getting a total rewrite for Fabric. Here's why.