Dark Forces is pretty comatose at the minute. I think most of the remaining active mapmakers were waiting around for DarkXL to launch with it's new editor. Dark XL hasn't had a news update for over a year and a half, and the community over there is losing faith in completion at this point.
DF-21 went down a couple times over the past few years. Lucius (the Dark XL creator) was handling hosting, but the hosting company took down the site and refused access to the files (evidently the authorized contact was never updated). Jon-T had a mirror of the site, and we've been rebuilding the site based on this mirror, the internet archive, and files gathered from the community. Not everything is re-uploaded, but the really important stuff is.
The DF remake for Jedi Acadamey has been dead for almost a Decade at this point. They were able to put out a 6 level Demo back in 2008, and it had some pretty nice work done on it.
https://jkhub.org/files/file/1540-dark-forces-mod/
For custom levels, The Dark Tide Series by Patrick Haslow, Matthew Hallaron, and Barry Brien had the last major release in 2007 with episode 4. It's a beautiful level with creative INF throughout. There's been a few smaller levels here and there since then, but nothing really groundbreaking.
DF-21 still has forums, added a subreddit, and even a twitter account. It's definitely a slow moving community; but we're stubborn and won't let Massasi take the crown of "Pointlessly 90s website that has no good reason to exist in this enlightened age" without a little bit of a tussle.
Cheerio!
https://df-21.net/
https://twitter.com/DF21net
https://www.reddit.com/r/df21/
Taton Qek, The master of masterfully inspired levels that never get released.