the first AI can describe the second AI as knowing that there is a 50% chance, but caring more about the heads outcome.
First of all this makes any sense solely in the decision-taking context (and not in the forecast-the-future context). So this is not about what will actually happen but about comparing the utilities of two outcomes. You can, indeed, rescale the utility involved in a simple case, but I suspect that once you get to interdependencies and non-linear consequences things will get more hairy, if possible at all.
Besides, this requires you to know the utility function in question.
First of all this makes any sense solely in the decision-taking context (and not in the forecast-the-future context). So this is not about what will actually happen but about comparing the utilities of two outcomes. You can, indeed, rescale the utility involved in a simple case, but I suspect that once you get to interdependencies and non-linear consequences things will get more hairy, if possible at all.
Besides, this requires you to know the utility function in question.