I don’t use wefwef.app, but I’m assuming the issue is to do with mander.xyz being an instance (like lemmy.world or sh.itjust.works).

The point being that any communities from mander.xyz will still show up if you search for them on wefwef.app

For example, I searched wefwef for the communities labeled mycology and it brought up the correct community from mander.xyz:

https://wefwef.app/search/lemmy.world/c/mycology@mander.xyz

Edit: in essence it search works for searching for a community, but not an instance as a whole; I couldn’t just search wefwef.app for mander.xyz and see all of its communities listed, but I can search for a community from it and it will come up

Just to test a theory: https://wefwef.app/posts/mander.xyz/local

This will show you the posts from mander.xyz as if you’re on that instance

Though I think these will leave not signed into your lemmy.world account, so I guess find the communities you like the look of and search it from your normal wefwef.app instance