I don't doubt the metaphysics of Earwa lends itself to Prophecy, but how could one living under Earwa's arrow of time sort out what will happen in the future?
Seems to me the difference between true and false prophecies is preference. Mimara may have something to do with the salvation/damnation mechanics, something the Inchies don't want to happee, so to comfort themselves they say the prophecy involving her is false.
Of course, if they think she's part of a false prophecy, why not have the skin-spy killer her? Seems like she may be a contingency, or perhaps trapping a woman with the Judging Eye into the Carapace is what makes a No-God....which explains why the Consult had to wait all this tine...