I spent more time trying to nudge the letters around than I spent actually thinking about the configuration. For a puzzle game, you want it to be the other way around, but I can see why that would be difficult to achieve for a game like this. A possible solution might be to have letters snap into place when the player sets them close enough to the answer. It would kill off the sandbox feeling, but it would fix the problem of trying small tweaks to get letters in place.