Is that the designed goal of CSD?
Maybe @Gazebo purposely made them not accumulate in the faith pool? Have you asked in that forum?
Are you sure it was a Great Diplomat and not just buying a Diplomat?
Not sure how exactly the acquiring of either would be the trigger of a Diplo Victory?? You would still have to use them to gain influence.
Edit:
More to the point, just how did you get to 'faith buy' those units in the first place?