Ideas and suggestions.

When will there be tournaments with bidding for castles? Then the picture of castle balance will become clearer. I think that if you offer opponents to take Dungeon in exchange for your Stronghold/Tower/Castle, there will be no shortage of those willing to do so, even without a rollback, and even more so with it. Regarding the Swamp – well, I don't know, the Dragon is good, but calling it a top-3 is a bit optimistic, in my opinion. Offer your opponents to take Rampart in exchange for your Swamp – I think there won't be any refusals either.