I'm not sure. Aumann's paper seems to only bill itself as leading to agreement - with relatively little discussion of the properties of what is eventually agreed upon. Anyway, I think you may be expecting too much from it; and I don't think it fails in the way that you say.
Why should ideal Bayesian rationalists alter their estimates to something that is not more likely to be true according to the available evidence? The theorem states that they reach agreement because it is the most likely way to be correct.
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