This is a genuinely good dungeon dive. The area is a small sandbox, and provide enough freedom that the players have a chance to explore the area without feeling railroaded. The initial hook is okay, but you can easily lure the players in by either offering a decent reward (50 thaler) along with an explorer's license. The encounters aren't a random encounters table of generic monsters, they are genuinely interesting and contribute to the environment. The major NPCs are actually pretty interesting as well, and the DM is given some freedom in determining how open they want to run the game.
By the time the players reach the actual dungeon, they should have had the chance to earn at least 30xp, as there are multiple scenes where it calls for master level loremaster. If you've been strictly following the Copper Crown series, you probably haven't awarded this much experience to your players. Granted, how many people actually rush for master loremaster?