The very first thing I said when I opened this document was “Hot damn! This is a lot!” (/complimentary). I feel like this document in its current presentation might be difficult to scale down, print out, and read at the table (but I’m up for the challenge!)
I’m struggling to see why you’ve tied these abilities to the Stormwight subclass. There are enough options, flavor, and versatility for this to stand on its own and be its own subclass (perhaps inspired by and following similar progression as the Stormwight). I feel like this is a more broadly accessible path versus having many of your options have “replaces <this Stormwight feature>” text. I see that you don’t have alternate versions of mid-game Stormwight mechanics, but I figure that you can rather easily rewrite and/or reflavor them to fit a full Zodiac subclass.
I really like the idea of switching your kit in accord with the diagram, as opposed to having free reign to swap at later levels - though I do think this sort of functionality comes on a bit late. It’s a nice piece of utility, but compared to the ‘Menagerie’ ability it’s replacing, is kneecapped a bit by having to follow the diagram, rather than just choosing a new kit from the list. Similarly, having this ability become available earlier could grant this as a subclass additional flavor (months and seasons passing throughout the characters’ adventures), while also showing mechanical distinction from the Stormwight offering.
As the absolute smallest of nitpicks: it threw me off seeing the ‘Effect’ before the Power Roll chart on the Sagittarius kit; but from a mechanics and ease-of-use perspective, I see why you ordered it that way.
Overall - this is a fantastic piece that I will wholeheartedly recommend and offer to players at my table. The theming, design, fantasy, and mechanics are all on point. I’d recommend formatting it into its own subclass, since that should help it clear the slight accessibility gap (it’s much easier to pitch and offer a player a subclass versus a set of rules to hack an existing subclass to fit their desires).