How does “This ship may dock at an enemy home island and load one treasure. If able, she must leave on your next turn.” work? Do you get to choose the treasure you take or is it random?
The player losing the treasure gets to pick the specific one you steal, so you’re unlikely to get something highly valuable unless that’s all they have. (The best time to raid is often right after their first ship returns home. Or, just make multiple raids.)
Also when trying to find an answer in the FAQ I came across the section for “Multiplayer”, which has among its exceptions from the regular 2-player rules that “Treasure is not revealed when unloaded at a home island.” This implies that you are supposed to reveal unloaded treasure in a 2-player game, which seemed odd to me as this isn’t actually mentioned anywhere in the rules. The rules just state that all treasure must be unloaded when you dock at your home island.
I’ve been playing that the treasure always stays hidden as it’s hidden when on the ship so it felt logical that it remained hidden when unloaded. Why is it the case that it should be revealed?
The rule to reveal treasure immediately is carried over from the illustrated rules, and ties into the “more than half” rule for ending the game. It’s not exactly the best way to handle the endgame, so feel free to continue ignoring those rules and keep using the multiplayer rules for everything instead.