No definite information yet. The Virtori are the most filled out, with a hierarchy that seems to resemble the Roman Catholic church, but we don't really have title names yet that I know of. We know from D&SS profession lists for settlements that priest and monk are names of professions, so this might give you a hint.
There may be character naming rules that prohibit the use of in-game titles as parts of proper names. All surnames have to be vetted by SBS, but we don't yet know anything about the restrictions on individual names. There is a design journal or developer journal that states what rules are already in place.
I would hold off if I were you. Also, you don't necessarily want to restrict your character in case, for instance, he gets promoted to abbot.