@goatsarah Humm... wouldn't the mention in the "missing" toot cause the toot to be sent over?
My understanding is that any direct interaction you make (fave, boost, mention) causes a request to be sent from one server to the other, whereas other visibility (federated timeline) is based on who is following whom.
@goatsarah For example, I feel like our two servers (thegoatery.dyndns.org and cybersecurity.theater) are probably not meaningfully "federated" in the latter sense—your posts that don't mention me are not going to show up on my federated timeline, and vice versa—yet we're still able to have this conversation.