When a "split" pile appears in the game, it states clearly that it is split, but I couldn't find anyway to read the bottom card. Thus I have to search the internet for the bottom card and it's description, unlike any other unfamiliar card which I can simply read in-game. Castles will probably have a similar issue, where a user will be forced to look at the list of castles outside the game to know how the rest of the pile behaves.
For random non-uniform piles (ruins, knights), obviously the cards beneath the top should be hidden, but one might argue that a list of possible cards should be available.
It's been remarked a few times that the current game client does not allow to show or select a certain set of cards. The "bottom" cards of split piles are the main culprit, but IIRC the prize pile for tournaments has similar problems.
Indeed, you can only see one card of the prize pile (for me, consistently, Trusty Steed)