Question about Knights & Merchants Palace - If I use the Palace to get a card back from the discard pile when the event “Year of Plenty” is rolled, is my Treasure Fleet nevertheless still effective?
Yes. But you can only use the “normal” resource for it, i.e. the onde you get when the Sun symbol is rolled.
Note: The Treasure Fleet belongs to the theme set "Barbarian & Traders", which is part of the Catan Card Game – Expansion Set.