I'll be honest, I haven't been up on this topic in a while. What you laid out is a bit daunting and not easily readable.
Also, I see no reference to the Jonadabs. While I agree there is no direct connection to 1919 chronology, I feel it is a critical piece of the appointment puzzle that WTS writers/leaders heavily rely on. It is the emotional part of the story that believers can latch on to, and is critical to how their theology and worldview remains up to the current period.
I once discussed in depth the 1914/19 chronology and selection information with an Elder that attended ministerial training school and was taught under a governing body member. Faced with the documentation that the 1914/19 chronology was incoherent, he immediately transitioned the conversation to the Jonadab "miracle". This point was communicated heavily to him during his training, and I believe it remains in the background as the "backup" evidence to 1914/19 JW leaders rely on to define their divine appointment.
The reality is no Jonadab miracle occured. With Rutherford at the helm of the Bible Student movement, membership in the group began to shrink because of opposition to the direction he was leading the group. Rutherford responded to the self induced loss of membership by saying it was part of a divine plan. The group would continue to shrink until the end, he predicted.
However, the great depression occurred creating an opportunity for the groups message to find a wider audience. Faced with explaining the new contradiction that membership was no longer occuring, the creation of the Jonadab class fixed the issue.
Simply relying on Watchtower publications, especially post 70s, it is easy to see how the context to these events was lost in favor of reliving the "miracle" of a "great multitude" unexpectedly entering the faith. The mythic origins help soften the 1914/19 scenario, the birth of the Jonadabs, 144,000, two classes of christians, ect.
On the whole, I feel that the 1914/19 discussion is far less important that the mythologization of the Jonadab class and the Watchtowers history around this time.