Still having a looooooong way to go in Xenoblade Chronicles, I've gotten a good feeling for how the U.S. "localization" went. As far as I can tell, they basically took the British "U"s out of everything and left the rest of the spelling in tact. Even the dates on the save file screen retain British ordering, displayed in D/M/Y.
This is not a criticism. I like it this way. It really fits with the British voice actors, too. And, as an American, I can't tell you how good it feels to play a fantasy JRPG where, for once, no one in the dub cast speaks with an American accent. It gives the game a more exotic flavor.