I think everything you have here is spot on!
You could maybe include something to clarify like what kind of sub-genre the group is imagining? Like you have the kind of classic medieval fantasy settings of the earlier games, but there’s also a lot of modern science-fantasy or even kind of cyberpunk(?) stuff with FF 7, 8, 13, 15, etc. It might be useful to clarify what your group is aiming for there when you all decide ‘let’s play FF Fellowship.’
On a similar note, this might bog down a collaborative exercise like this, but I feel like each FF game always has some like… core narrative x mechanical gimmicks? Like in FF7 people don’t use magic naturally, they have to use materia, which is actually the crystallized essence of blah blah blah… FF8, people draw magic from natural sources and junction it to use para-magic, etc etc etc. You already have divinities/summons in the Great Powers section, so maybe it’s an expansion of that?
You could do some silly little details that are staples in FF, like “what is the lovable, strange animal that people ride in this world?”