Old North,
Not my experience, BUT, I was playing with the latest patch which came out June 2017. I've not seen much anything negative since then so if there were issues they don't seem to exist now. But it is a MANUAL interface, not an automatic digital transfer. I got a very negative note about my review and I think this might be at the crux of the matter.
When you hit the miniatures option for battle, the game saves the numbers and stops. When you finish your mini game you reload the game and it presents you with a screen to fill out. It asks you to declare a winner and for each unit to provide the end of battle strength, morale and fatigue in the format it understands. That means you have to convert your game results into Danube format. For example if Delzone starts the mini battle with 12 Danube strength points, that 6000 men. If my mini game is Age of Eagles and Delzone loses 4 stands, that's 1440 men or in Danube terms, 3 strength points. Thus when I fill in the screen I type in 9 as Delzone's new strength. Some simple math conversion is unfortunately necessary, but it does mean you can use nearly any rules with it.
For the review I played both an 1805 and 1809 campaign, no biggie because historically they were very short. I took three computer battles as miniature test cases. One I used the HPS Campaign Eckmuhl game to resolve the contest, the other two I plugged in numbers from two AOE playtests I did many moons ago. The computer accepted the numbers I provided, made the necessary changes to the units involved, and play continued without a problem.
There is an ancients computer game coming out with a direct digital transfer interface for miniature play. Its called Field of Glory: Empires and it directly interfaces with the Field of Glory miniatures game, but the computer game version thereof which was also designed by Richard Bodley Scott, the pewter rules designer. Likewise C&G has a similar system under development, but again its only designed to interface with C&G.
Outside C&G, if you want to use a PC game as a campaign system and battle generator, I think its going to have to be manual. Right now Danube is the only one I know that allows that and the fact there haven't been any more games designed to do that indicates that part of it likely wasn't popular.
But then again, there are always Kevin Zucker's campaign boardgames.
weg