An excellent article. With a fifty years of involvement with Japan and living in Hawai’i (in many ways a ‘ken’ of Japan) I have hope for how this may evolve. It is always a surprising culture that manages to make good things happen from complete disasters. The problems need to be fixed and, in my case at least, it is not a love affair but a marriage so you learn to live with foibles and errors and encourage their correction.
In reference to the length of the jidai, I think they followed the Chinese dynastic model directly (it all started with that intent) but things became more confused after Muromachi and the wars between rival military leaders. Obviously Tokugawa was a dynastic name and Meiji made it a reign name to show the break with the military ages.
But who knows. You actually need to find the right person to ask in the imperial library but, this is Japan, it will almost certainly not be anyone with a title and big office.
My Japanese history advisor, who had received permission to do research in the imperial library, told me the story of days that he spent having tea with officials in nice offices with no clear result. One day one of the employees stopped him after another long session with tea and suggested that he talk to the man in the small office in the basement. He did and discovered that the man in the small basement office was the person who actually controlled the entire library. The other people were were only for show.
If you find that obscure but still charming than you can be at home in Japan.