I’m not sold on the subdomain used for the forum.
If we were to change the forum software at some point (and who know, it might happen), then having the subdomain be named what the software is now/then was is not great.
Also, using the more conventional “forum.” as subdomain is well established and easily understood and identified by everyone. Honestly I think there’s people who don’t even know what the word discourse means, and even less heard of this forum software before, and even less would think about this being a forum if they see a link named Discourse. And if we instead name the forum “forum” in text and links, then why on earth not use that as the subdomain as well?
Do we really want to stick with “discourse.” as the subdomain for the forum? Now’s the time to change that, if we want to.