Hrm. As I understand it, the theory underlying CEV doesn't equate X's best interest with X's desires in the first place, so the question is somewhat confusingly -- and perhaps misleadingly -- worded. That is, the answer might well be "both". That said, it doesn't claim AFAIK that the end results will actually be what every individual currently desires.

Does CEV claim that all goals will eventually cohere such that the end results will actually be in every individual's best interest? Or does CEV just claim that it's a good compromise as being the closest we can get to satisfying everyone's desires?

The latter.