Road movement/enemy encounters

A common situation is to have several brigades advancing along a relatively wide front (potentially along multiple roads) such that visual contact with both at once is not possible. For better speed, the “Road Column” formation is the best choice while moving; however, upon encountering enemy forces this formation is highly vulnerable.

Does the AI reorganize its units from road column into a more suitable formation upon sighting the enemy?

Almost all of the time I have observed this to be the case. Rarely I have a problem where my artillery seems to get away from their commander and they become unresponsive. Otherwise I find the brigade commanders to come to a halt when they spot the enemy and then form an appropriate formation according to their stance. The enemy AI operates under the same rules as the player commanders do as far as I know.