A tricky part here is that the community still needs to be followed at least once on your instance for the content to come through. *I think*
So if a community isn't coming through, I'd recommend these steps:
* Search for the community and follow it like any other user.
* Add it to a specific/bespoke list, then remove that list from home (a setting available on each list). This removes "the firehose" from your home feed.
* Follow the corresponding tag as you would any other