A member of a tribunal told me that a valid, consummated, sacramental marriage can be annulled on the basis of “incompatability of faith. What can you tell me?

The Church’s Code of Canon Law states:

“A marriage that is ratum et consummatum [meaning valid, sacramental, and consummated] can be dissolved by no human power and by no cause, except death” (CIC 1141).

I suspect that you misunderstood the tribunal member. To say that a valid marriage can be annulled makes no sense. An annulment never invalidates a marriage—it simply recognizes and declares that a valid marriage never existed. There are cases, however, in which a valid marriage that is either (1) not sacramental or (2) not consummated may be dissolved, but dissolution is very different from annulment in that dissolution actually ends marriage.