How to re-order a mini-panel in a Panel generated page?
Okay, so I ended up finding my own answer while working on something else. I realized my scope was wrong, I was looking for an override page referring to a specific page type/section, but what ended up being the case was that there existed an override page for all nodes with unique content/layouts in use for each of them within the same area.

So there was ultimately a Panel Page doing the dirty deed as I had thought, but I was being too specific in where I assumed the changes were made, in part because I assumed an override page would have to maintain the same layout for all pages it overrides, but that's not the case I've learned.