Is it possible that one or more of the diviners could become corrupt and use their "visions" to enforce their own agendas?
Yes, if they are more like Yaphyll and less like Zalathorm.
Zalathorm surrounded himself with fellow diviners, as I recall. Each of which could have, potentially, taken it upon themselves to manipulate possible future events for personal gain.
That is why I zeroed in Zalathorm himself. It may sound too unlikely to have an assembly of good-alignged or neutral diviners, but it's not far from possibility either. If lawfully good deities could recuit worthy people to their cause, I guess some agent could do the same to diviners.