I found it!!! What is it?, you may ask. I found an online version The Castle in English! I played a couple games on brettspielnetz.de, but being entirely in German I felt like I couldn't quite follow everything that was going on. It was very tedious.
The English site seems almost identical as brettspielnetz.de, except for English and different colors.
Sign up for an account at yourturnmyturn.com -
http://www.yourturnmyturn.comBy the way, Carc: The Castle is just listed as 'Carcassonne', but it is indeed The Castle.
I'm Sesquipedalian on yourturnmyturn.com, so find me if you want a game.
Enjoy!