Scourge of War Boards

In that case, what is the problem with setting maximum range to a realistic number of 100-120 yd?

Because it is a minimal range I evaluated is good for have all the potential dangers checked every loop in time , still having sufficient space to move without collisions, and without go over the max firefight ranges of period reported from the sources. It avoided the problem to check the enemies too often.

Does the AI adjust its lines when the enemy comes into view or does it wait until the enemy is within the maximum firing range. For example, if the enemy moves to the flank of the AI, doe the AI wait until the enemy is within firing range to respond or does it begin to face the enemy when it is first 'seen'?

yes there're a set of cases where it wheels to face the nearest enemy out of range, respect Gettysburg I put some control in order to minimize or correct after the overlapping. Some cases are managed only for AI controlled brigades in order to leave to the player the decision to what to do when it controls directly the brigade.