Air is vaguely synonymous with movement at a physical level, and living social interaction at an abstract level.
Earth is vaguely synonymous with fortitude and steadfastness at a physical level, and otherworldly spiritual interaction at an abstract level.
Fire links to violence and conflict at a physical level, and emotional drive at an abstract level.
Water links to calm and focus at a physical level, and deeper knowledge at an abstract level.
Void exists at the centre, linking metaphysically to a character's inner enlightenment.
(Yes, it's all a bit L5R, and Musashi...)
The problem with switching to a Chinese paradigm is the fact that Air doesn't exist in the five elements, nor does Void. Instead we have Wood and Metal. The other issue is that the Japanese elements are aligned in a cross shape (quincunx), while the Chinese elements are depicted as a pentagon/pentagram with their various interrelations.
It's a fundamental shift at the centre of the game.
I could simply rename "Air" as "Wood" since a lot of the affinities still apply the same way. Similarly, I could rename "Earth" as "Metal", then re-introduce a new "Earth" element. It will require some shuffling of which skills fall into which elemental categories.
Otherwise, I could maintain the notion of four points around a central focus if I organised the game around feng shui principles, with 4 cardinal directions (each bearing their own correspondences)... But again, the correspondences of the directions don't exactly match the ones I currently have in place for the Japanese elements.
And then everything falls into place.
Tibetan buddhism has the same 4 elements I've been using, while maintaining the 12 animals, and the other ideas I'm using.
It evens brings into play the idea that the five elements can become corrupted and thus become the five poisons, which could easily link back to the five toxic animals that +Ian Borchardt mentioned in a comment to a previous post.
Setting the game in Tibet also anchors the game to a specific conflict if it's set in the modern world. Hell, there's conflict between various belief systems and regimes at almost every time in history for this region.
I'm seeing an inherent caste system, with the 12 astrological animals as an upper caste (which the current highest level held by the animal whose year it is), the vast majority of animals existing as a middle class, and the five toxic animals as the lower castes. Vultures, being a sacred animal in Tibet, would exist outside the caste system (perhaps akin to winged monks who shepherd the souls of the dying to the next life...almost a Tibetan equivalent to Valkyries).