When you start a new game the xml files seems to be stored into the save game data. According to Paul this is to prevent updates breaking a game.
However when testing (or fixing a xml problem) it would make more sense to be able to reload the - changed - xml files into the current game save. But this should be available to testers/modders without burdening the regular player (because of the game breaking risks).
I therefor request that if/when this is supported then either through a command line option or a command in the debug window.
Of course this could lead to cheating, so the game should mark such a game as not eligible for rankings or achievements.