The DPCNA decided to retain the difficult to pronounce native name with the intent to help ensure the Drent stayed true to type and form - One Drent. Besides Dutch Partridge Dog, as the English translation typically goes is terribly generic and threatens to pigeonhole the Drent as a ‘one trick pony’ here in North America...As for those in the know, the Drent is so much more.
As far as pronunciation goes, when in doubt, just say Drent.
I'm just a guy suffering with an infatuation with gundogs since childhood. Fifty some years later this is what you get.