The left controller (primarily) controls the left pack of course, its also the backup for the right pack and vice versa. The left controller primarily controls the trim air modulating valves for the zone temp which supplies the aft cabin air, the right controller controls flight deck and fwd cabin....
Re the recirc fans (Guess mode on..) . Mostly, you will enter high flow following pack failure of the opposite pack. Regulations require a certain volume of FRESH air per pax, so if on a single pack the recirc fans are on, maybe Boeing worked out that the volume wasn't guaranteed. Hence, they get inhibited? Maybe? (Guess mode off...)