Bots of this type have appeared recently, and people are asking if it's okay to use them. I'm not sure about this either, so I think it would make sense to ask users.
These bots follow some subreddits on Reddit and automatically post it to Lemmy when a post is created there.
I've seen an example site for it: lemmit.online. This instance is dedicated solely to mirroring Reddit posts to the Lemmy instance.
Maybe instead of mirroring to a community on Lemmy NSFW, we can subscribe to lemmit.online via Lemmy NSFW. This way we could have kept Lemmy NSFW free of bots. Currently, even if accepted, I believe it should be done under admin control to prevent duplicates.
As for different communities, people who don't want to see bots can disable them in the user settings, so the communities wouldn't change for them. I don't see the point in having bot communities.
No, I assume that the bots would only repost the most highly voted content. If a bot were to post everything, including low-quality content, the moderators could simply ban it.