Jonadab class is an older JW reference, I use it to refer to the change around 1935 that discerned the difference between the other sheep i.e. great crowd/multitude and the anointed.
The olympic efforts of reasoning required to arrive at 1914 using the bible is strains credulity enough. The leap to 1919 is the icing on the cake in terms of how self serving these beliefs actually are.
To get back to Mr. Mason's original point, I would argue the precise method used by the Watchtower Society to show that it was appointed in 1919 CE looks something like this:
A great question just came to me. What is the last year according to current JW teaching that the WTS/anointed fulfilled bible prophecy? I'm sure it is whatever is in the Daniel or revelation book. My assumption is that once the Knorr through Franz era kicked in the organization stopped fulfilling direct passages of scripture. The mythology was "set" so to speak, with no need to update that part of the story. At this point their books assume the continuation of the current postwar geopolitical world order with no major shake ups, giving the necessity for predictive concepts beyond generalities inessential.
I'm speaking directly regarding the WTS fulfilling prophecy. Not government entities or other world events.