Suggestion:
Raiders should have destruction of depots set as a high priority.
CSA has been capturing depots that it then leaves intact while moving on to capture other cities. Raiding AI units don't seem able to destroy depots though they are happy enough wrecking rail. Not sure if this is an oversight but I have never seen the AI destroy a depot. An army capturing a depot is different as they might actually stick around to use the supply one can provide.
The Good:
Just played about 6 months of the April 61 campaign as the Union and was much impressed by AI improvements. CSA counterattacked successfully at Fredericksburg, attacked ungarrisoned cities promptly and went for weakly garrisoned cities too. Also counterattacked cities where I was overextended. For the first time I was suffering double the casualties of the AI. Very impressive. Had to change the way I played.
Also note: the AI might use some tweaking when selecting which rails to destroy - they don't seem to be breaking any/many key east west rails in the games I play. I generally keep the AI too busy reacting to my moves to raid too extensively so this has become noticeable.
Final comment:
Not certain about this but besieging AI troops don't tend to destroy rail and thus reinforcements can disadvantage the AI player. I suspect the AI would be a stronger player if it blew rail as a matter of course.