The Steam Users' Forums offer downloads and details on a new user-created patch for Anno 1404/Dawn of Discovery: Venice. Word is: "I'm the current Admin of the Anno 1404 English Wiki, and after doing some extensive testing, I've found a method to modify the fully patched game and not break achievements." The patch is also mirrored on Gamer's Hell.
Oh you are right. My unofficial patch works with all other languages as well, although you obviously don't get the English text fixes. Still, you get all the game, quest, and achievement bug fixes.