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.