TC39 uses Matrix for its discussions. We would be spreading ourselves too thin, I suspect, to have more than one "official" location.
Nice. Matrix is a good call. You mind posting the link?
Matrix could still be the main place for discussions. Discord is mostly being used to have Announcements, updates on Pull Requests, Commits, etc and generally having contact with a community. Similiar to an Newsletter.
Due to its extensive API a bridge between Matrix and Discord would also be possible.
We actually did discuss using Discord before settling on Matrix. The main blocker for Discord was that its terms of service do not clearly permit posting public logs, which is a hard requirement for us, and we weren't able to get them to update their terms of service to allow this despite several rounds of back and forth.
Now that we're committed to Matrix I agree with @ljharb that the costs of switching would be too high, even if the logging issue were resolved.
whoops, sorry, i did post the wrong link :-) That's the Matrix I meant to link to.
What I'm trying to say is that channels for, for example discussions aren't required at that point, but any information about where to actually discuss, etc. would be really useful.
If the effort setting this up is too high, I can also help.
An official space needs to be populated with delegates and staffed by Code of Conduct team members, at a minimum. It's unlikely that would be achievable for a secondary space, and I think it thus wouldn't be particularly valuable.