It wasn't clear enough that you were looking specifically only for DCG campaigns.
Some people have told me over the years that IL2DCG campaigns are not possible in BAT after certain year dates
but was told IL2DCG cannot do it for BAT?
But
if there really is some limitation or problem, it most certainly does not have anything to do with BAT as such, but with DCG itself. Maybe it has a hardcoded date limit? That is within the tool itself then and has nothing to do with BAT. No idea. Then the available old campaigns would maybe use fictional data as well (Say 1942 as set value instead of an unavailable 1952?)
BAT does not impose date limits on the era modules. You can make a static JTW jet mission set in 1914 in the .mis file, if you want to....
Well, shakaali would definitely be the guy to talk to about such a thing.
You'd definitely need a DCG person to help understand the exact nature of the limitation and what's needed to overcome it. But don't let someone tell you that BAT is the reason for any of this. The Skyhawk or Wyvern in BAT JTW is literally exactly the same as if you'd add those to your DBW, for all DCG is concerned.