Lemmyverse.net show both communities: https://lemmyverse.net/communities?query=watchreddit
It probably didn't show up in the first place it only has 66 subscribers, and probably none on SJW.
About your second point, you indeed have to promote your community, using !newcommunities@lemmy.world, or related communities. This works quite well usually.
I will add that in your case, people knew about your community as you posted in other communities, but as discussed then, people seemed happy with the existing Reddit-focused communities.
Enjoy, feddit.de is a great instance