So in Eliezer's meta-ethics he talks about the abstract computation called "right", whereas in e.g. CEV he talks about stuff like reflective endorsement. So in other words in one place he's talking about goodness as a formal cause and in another he's talking about goodness as a final cause. Does he argue anywhere that these should be expected to be the same thing?

Not explicitly. He does in various places talk about why alternative considerations of abstract 'rightness' - some sort of objective morality or something - are absurd. He does give some details on his reductionist moral realism about the place but I don't recall where.

Incidentally I haven't seen Eliezer talk about formal or final causes about anything, ever. (And they don't seem to be especially useful concepts to me.)