That is an amazingly apt and well-thought-out analysis, and a joy to read.

I think I've seen others call Lulu and Auron the Mom and Dad of the party, or perhaps chaperones.

The interpretation of Yuna as universal love, and the reason why she can't do the Final Summoning-- perfect. All the summoners before her chose to focus on a personal love, so they couldn't save everyone!

I also love characterizing Kimahri's devotion to her as chivalric. Perfect. I was just reading Gawain and the Green Knight, and that fits so well.

Lulu's a bit puzzling -- sisterly and maternal. That's a common blend between close-knit older and younger women. She's more maternal though.

The only one I'm not quite sure about is Rikku. She's such a free spirit, it's hard for me to pin her down. I see what you mean, though.