It really is a shame. This game is amazing. I'd love to see an ACW version as well. Is it moddable in any way?
Yes it is. But it is a lot of work . There are two files for one scenario, i think *.adx and *.amx. One has all the map information in it (terrain, roads, rivers, bridges, ...) and the other one has the information of the rest, like starting date and end date (if you set the dates in a winter month it can snow), armies oobs and qualities of the units, victory conditions, etc.
If you have a lot of time and you know something about hex editing you have a chance to do all scenarios of the napoleonic wars and acw. Use a spreadsheet, where you can implement some usefull calculations.
What i don't know is, if you can change the calculations about combat, etc. But i think it's hardcoded.
IMO you can make a lot of the 18th to end of 19th era operational scenarios. I think, there aren't any railways in the code, but you can implement a date and hex, when and where a unit will arrive like reinforcements (for example Jackson on the battlefield of Bull Run).