Hey, thats a really nice Guide. It works for me (still not perfect, but its something - AI determind without boost)
But Step 3 was a little bit different in my game: Devins' Skirmishers do not try this suicide move (I was just about to restart because i tought i did something wrong) but instead the Iron Brigade and Cutler moving forward towards Archer, Davis, my Skirms und all the Artillery @McPherson. and they get absolutly crushed, so the rest of the battle was pretty easy.