

Streamlining cross posting is a good idea, as long as someone actually read the post and posts it with a purpose. On second thought, I think cross posting is simple enough, given that titles are usually auto completed.
I’m generally against automatic cross posting bots, as they usually post duplicates, bad articles (instead of a proper source). Additionally, they often flood communities with an amount of content they are too small to handle. I.e. a lack of users to vote on posts let’s good articles drown in a flood of mediocre posts. This can kill communities as they feel even more empty than with fewer posts but more comments.
If there’s not enough moderators subscribing to subset does not make sense. The idea of subscribeable moderators is interesting though I don’t expect it to be implemented. Duplicate communities on different instances serve a similar purpose already.