As a UX Designer with limited coding abilities this looks very interesting. I tried to describe a little feature that we will need to build soon. That was pretty straightforward, but I also felt very limited as there was no way to comment anything in the spec.

But it can be really helpful to think through all the states that the application can be in, something I often neglect. Not sure if I will automatically think through the non-happy paths, but it might help.

With a more fleshed out syntax, I could very well see myself using this. But I don't see myself using the Javascript / prototype part, if I actually to that I could probably just create a prototype in Vue.js, which then also would describe all the states. I would focus on the spec part and make that more powerful.