Army size and battle duration are under scrutiny.
Good. Probably don't matter to many players, but certainly irk ACW grognards like me.
Battle results: once again, you have't fought against Banks, only against one Union Corps. Look at the battle results panel: there's no Union 3 stars General, only a 2 stars one. So the uNion corps was heavily hammered by your more larger Confederate Army, explaining both battle duration and loopsided losses.
Right. I had forgotten that. Confusing nonetheless.
About Grant, only new games with the latest version will fix this. On this point, your current game results are more and more below the current Union AI strength.
I failed to mention: I see much Union activity at sea, and many fleets sailing up and down the Atlantic coast. But nothing beyond that yet.
At what point would I best abandon this game, and start over? Or is this still giving useful feedback?
IMO, it would be now better to start a fresh game. In my own current new test game, the Union AI has disembarked an infantry brigade and a cavalry regiment in Florida in September 61. After having captured a coastal city, the target is Ft Marion. However, there's yet no naval bombardment of the fort. I'm going to wait a few more months in the game to chack why.
On the contrary, UnioN AI is very present in Kentucky; your own test has showed Missouri Arkansas and Eastern Virginia were rightly handed by Union AI after the first months phase, whith right paths of offensive and without catastrophic failures due to a cut of Union supply lines, that is satisfactory. Union AI may go deep but there's no madness in the moves.