D:OS2 had an officially supported campaign creator. It never went anywhere because by all accounts, it was awkward to work with. I honestly wouldn't be surprised if whatever tool BG3 comes up with meets the same fate. Fanciness shouldn't take precedence over ease of use.
The above is literally the only custom campaign I tried out for D:OS2, some 2 or 3 years ago. I am also heavily unsurprised that it's probably the only well known one. Digging around in google tells me that a community focused on creating custom campaigns in DOS2 straight up doesn't exist. I'm also not surprised that Larian has yet to promise a campaign editor for BG3 as a result.
