I'd be very concerned that the "cleric" ability would just get the adventurers ordered about as, effectively, portable shrines.
Similarly with the "bard" ability, it would be likely to have realms start treating adventurers as morale-machines.
Bear in mind that, unlike nobles (who do indeed have many of these types of abilities, and are sometimes treated as mindless machines, but far from always), adventurers a) cannot go to battle, so any new abilities they gained that would help a realm would instantly put them from the "probably more trouble than they're worth" column to the "exploitable resource" column, and b) can be hunted down and arrested by nobles if they ever refuse to do what they're asked.
The occultist doesn't have that drawback, but it also doesn't seem to have any reason why all adventurers wouldn't be occultists. I would very much prefer to avoid classes (and other choices) that are "must-have".
