I quite love how much it focuses on the coin and its mechanics, personally, really feels like this Spark is meant to go with a CoinSides and that the coin is the whole scenario, the circumstances around it are almost incidental!
I would suggest maybe making it clearer in the scene itself that the Retrieval Specialists are from the Observatory, as I didn't quite get this until I read over the whole document, and the players would probably react very differently to two randoms asking for the coin as opposed to people that hired them arriving for it.
It does make me wonder why they didn't just send the Specialists in the first place, but then, that's always how these things go in media!