If anyone votes on an old comment from the source instance, your newly subscribed kbin instance will grab the older message when the new vote comes in. Works with both Lemmy and kbin sources.
If the comment voted on is a reply to a reply, it will load in all the parent comments as well.
If you have a login on the other instance, you can vote and unvote and it will still populate your kbin comments.
Although I’ve found one area that Lemmy to kbin doesn’t seem to work when bringing in older content when a new vote is done.
Instance: StarTrek.website Lemmy. comment thread: https://startrek.website/comment/2051539
The copy on kbin.social does not seem to load the thread that starts with user @jet
https://kbin.social/m/quarks@startrek.website/t/404007/Favorite-sci-fi-film-thats-not-Star-Trek/oldest
Not sure what is going on under the hood where those won’t copy into kbin.
I think hackertalks.com is misconfigured, their posts do not federate to kbin. And I cannot add their magazines to kbin.social.
My best guess : https://github.com/LemmyNet/lemmy-ansible/pull/114