Wow, wonderful of you to make this. It really causes a lot of burnout to make things over and over.
I will need to play with this to make more informed opinion, but based on description and info on landing page, I love what you are doing.
One thing that crosses my mind, clearly not applicable in this case as you are far along, but making it more interesting to write these specs would go a long way on improving how people use this. Like, I would consider some kind of markdown or at least TOML... something with indentation as opposed to braces.
Anyhow, anything that would save me from writing boilerplate code is more then welcome.
It would be cool if there is a standard way and then people start making plugins and stuff. It would have to be open source as VCs spoil the thing.