I like the idea of figuring out the dice. But in terms of the dice manipulating him, I'm not sure they do. They warn him that something significant is near to happening, but he never knows what's up and can only guess at what will stop them. It always surprises him when they stop. So I don't think they're causing him to do anything.

On the other hand, the other function you suggest - the chronicling and reporting back to the Finns, that seems more supportable. One possible flaw in that theory is that they seem to be able to read anybody's experiences. But then again do we know anybody else who has visited the wish-granting Finns as opposed to the question-answering Finns? Can they only read the experiences of the people who have come through the ter'angreal and gotten their wishes? I dunno, just wondering whether dice in one's head are necessary for the Finns to know your experiences.