This issue of jhanas is related to that of “breath meditation.” It seems to me that questions will keep coming until both issues are tackled in a comprehensive manner.
I will start writing posts on jhanas as well in a comprehensive manner referring to the Tipitaka, just like what I am doing with the Anapanasati. See the first post “Ānāpānasati – Overview”
– Hopefully, I will finish the first such post on jhana within the next two weeks.
P.S. Any questions/comments on either of those issues need to be discussed at “Posts on ‘Elephants in the Room’“