Thank you Pharan for sharing!
AFAIK (Saturday jp class years ago is no help at all, google translate to the rescue.), the SDK looks to be in the paid version only, costing at least more than the price of a unity pro subscription, even with the small firms (rev <10k$usd~) discount. The exports from the free version is not licensed for commercial use unfortunately.
BTW, I think Toon Boom Harmony is offering less for similarly high subscription cost, eg no use of deform tool if you want to export as a skeleton.
Yes it looks like a useful educational tool for us, at least it shows me that the sliders are a nice way to experiment/tweak the animation's parameters. eg delay, strength of wind blowing on the hair (weighted to some bones I guess) . I'll try to do the same in the Unity Inspector in the future and see how well this way of composing animations can be done with Spine.
I can't even imagine what hurdle I'll run into, I guess I'll find out one step at a time 🙂