By the way, Piefed does not pull in remote communities by default. It only does it once a local user subscribes. And that's why a lot of them are missing on my own instance.

Oh yes absolutely - and Lemmy is the same way, so this too is not something specific to PieFed. For instance, that post I mentioned previously where my vote counts are all over the place, when viewed from StarTrek.Website has zero comment associated with it, and no upvotes beyond the default - and I have another post that is the same way, though it seems like later that same day someone subscribed and from that point onwards the community starts to have comments and some of the votes seen from other instances.

Or perhaps it is that these posts were locked somehow / for some reason? Which looks to be accidental from a new, inexperienced moderator in this brand-new community, and it was reversed a couple of days later - although that fact again depends on where you look. With an account at StarTrek.Website, I look at the post moderation history and it says that it is still locked: https://startrek.website/modlog?postId=16510256. However, with an account on DiscussOnline (substitute with whatever other alt you may have - hendrik@lemmy.ml?) I see that not only was it unlocked, but that unlock event happened 7 days ago: https://discuss.online/modlog?postId=13575162.

Even so, the post when viewed from DiscussOnline shows 98 upvotes and 8 comments, but when viewed from Lemmy.World (where the !tech_memes@lemmy.world community is located) it shows 191 upvotes and 9 comments (or I think it's 193 upvotes and 2 downvotes, but the web UI no longer shows those individually, unless you jump through many many, undocumented, hoops - e.g. I think I can see those broken down into their individual components on a mobile device in Firefox, possibly solely when viewing a individual users list of posts but not when looking at a post directly or in the standard community view, and definitely you cannot see this breakdown from either Chrome or Firefox on a desktop, etc.). And since it has been 7+ days, this is now enshrined in stone, and we can be confident that having not caught up by now, it never will. A decade from now, if e.g. DiscussOnline is still with us, it will show this post as having 98 upvotes rather than the true value of 193, and StarTrekOnline will still show the default upvotes=1 and no comments, thus providing 3 different stories for this same identical post, depending on how you try to view it - and only one of those stories being explanable by the fact that nobody on StarTrek.Website had subscribed to the community yet (MAYBE, b/c there are 2 other posts that are even older in that community, which have +1 upvote added!? so perhaps this is a complex mixture of that + the locking effect, with the unlock action having not been propagated correctly).

The above stories reveal - federation is NOTHING AT ALL LIKE EMAIL. In the latter, the message either gets passed or it does not, whereas in federation, you can see partial messages as I've shown. And this has not even begun to delve into the variety of defederations that further complicate any mess - especially with a unidirectional defederation where one account can talk to someone on a server that has defederated from them, though the recipient will never be alerted to that fact nor have the capability to respond. Thus it is my opinion that trying to fit the square peg into the circular hole is never going to work - the email analogy is hopelessly simplified, so much so that as soon as users begin to encounter such complexities when they make their posts, especially the content creator types that we very much want to come here, they may outright leave, and moreover be very vocal about how we are not what was promised to them. So while we could say "it's a little bit like sending email", I don't think we should push too hard on that avenue, making it sound so simple, b/c it's really not!