We have a lot going on in the discussion. There are many possibilities, and sometimes it's going to depend on your own "leanings" to determine which you think most likely.
Just focusing on the Popess....
1. She was originally Sister Manfreda in the Sforza Visconti (or a nun in habit of some sort), and that developed into the Popess.
2. She was originally Faith, (such as in the Cary-Yale Visconti), and that developed into the Popess.
3. She was originally "The Church" in iconography, and that developed into the Popess.
4. She was originally Pope Joan, and that developed into the Popess.
5. She was originally an Antipope, and that developed into the Popess.
6. She was originally "just a second pope", and that developed into the Popess.
7. She was originally a female religious figure (Isis, Mary Magdelene, Virgin Mary), and that developed into the Popess.
8. She was originally a Female Pope.
9. Other ideas I can't think of now or have not been brought up.
As far as I'm concerned.. ANY of the above could be true.
So we're left with looking at the decks, and the iconography of the age, and the history and literature and social context... and trying to put the puzzle together. I like to explore all the possibilites as sometimes one wild suggestion leads to a real fact or consideration that adds depth to our accumulated knowledge.
One thing is pretty clear though... that when the Viscontis made a deck in the mid 1400's, *they* certainly considered the figure to be feminine.
As far as I know (could easily be wrong here), all records show her being refered to as The Popess, and no other title.
So that forces one to consider... well.. Did the Viscontis invent the Tarot? If so.. then that is what it is. If they did not, and they got the 22 from another source, then we need to figure out what that source likely was to begin to get a sense of what the Popess might have been, if indeed anything but a Popess.
I've *personally* been leaning towards the Bologna pattern. And I tend to give extra emphasis to decks that don't have the titles or numbers.. because I presume that the earliest Tarot decks did not have them. IF that is correct, then the possibility for "misnaming" is opened. And when we're dealing with the iconography of the early decks, I think it is fair that "misidentifying" went on as well. That's not to say that I discount decks that do have the title and numbering, as I have stated elsewhere, I believe that the TdM originally did not have titles or numbers either.
Unfortunatly, we don't have examples of too many early decks. There's several in Kaplan's books to explore. We've got the Cary-Sheet, and the Metropolitan. It's frustrating that the earliest TdM we have is from 1650. That's 200 years! And the existing Bologna is from around the same time, (although we can guess at a lot of the iconography by looking at some early sheets and painted decks).
Maybe I've already cornered myself too much into my own "leanings" to look at things with a bigger perspective, but on the other hand, I do believe that I am not convinced that any of the above mentioned theories is "correct", and I am still trying to find clues to help sort it out.