I doubtless don't know even the trivial one
The Battleground Editor is just one of the "Game Tools" off the Main Menu. I'm sure you'll have seen it, and it's probably only a terrain editor... yep, just dared to have a look, that won't be what you mean.
If there's an easy way to set up test battles where you can import "yours" & "theirs" from what's happening, that would be lovely....