Have you ever seen absolute trash products get in front of your eyeballs repeatedly? thats because whoever owns that product has a really good marketing team OR is hiring one if they dont want to have one on staff.
Discovery needs a Marketing team who is responsible for taking and editing together videos and other material to promote the mod in the wider online world.
If you dont want to do that then hire an outside company, get costs and estimates then perhaps ask the forum community if they would be willing to crowd fund the effort.
Imagine having a new golden age in 2021
Even if we assume that everybody that ever played has 3 alt accounts, thats still 9000+ people, I think a newsletter to all current forum members should be the way to go as a start.
Its always easier to re-attract your current or previous audience members rather than looking for completely new people.