I think a lot of people browse ‘all’, so creating the community and then going to the main instances and subscribing to it from there is a good way to get it to show up in the Feeds.
Then post lots of content to the community to jumpstart it might work?
Hey, a little late, but maybe contact the Admin for lemm.ee they have horizontally scaled lemmy and it seems to be working. There is a config setting to disable scheduled tasks which should be disabled on all but one from what I remember, and then load balance across the rest