I don’t think it should be done by a specific name, it should be user defined, I should be able to add the communities together which I deem that they do belong together for some reason.
This.
People are used to a single handle mapping to a single community, and I get that they want that to still be true, but it isn't here. It just isn't. Having a communities auto-group in any way is asking for a bad time for all involved.
First of all, people generally are not considering the contexts that those communities are situated in. My go-to example here is politics communities. r/politics is, very frustratingly, about American politics, but that isn't going to be universally true here for communities named politics. You should not assume that an Australian based server, a Canadian based server, a UK based server, an Indian based, etc. will reserve that name to deal with, well, foreign politics. And having them automatically lumped together will functionally destroy the communities on instances focused on smaller countries.
In top of that, it's wide open door for troll instances.
If people want lists of communities, that's fine. That's great even. I'd love to lump together some sports communities so that when I'm in the mood for that, I can find them all in one place. It'd be cool to be able to have them optionally not show up in Subscribed, too. But auto-grouping is one of those features that is actively bad for smaller communities, and which people really only think they want. It's more of a sign that people aren't opening their mind to this new space and paradigm they find themselves in than an actually useful feature.