From what I was able to understand during the interview there, it's not actually a language, more like an orchestrator + pinning of individual generated chunks.

The demo I've briefly seen was very very far from being impressive.

Got rejected, perhaps for some excessive scepticism/overly sharp questions.

My scepticism remains - so far it looks like an orchestrator to me and does not add enough formalism to actually call it a language.

I think that the idea of more formal approach to assisted coding is viable (think: you define data structures and interfaces but don't write function bodies, they are generated, pinned and covered by tests automatically, LLMs can even write TLA+/formal proofs), but I'm kinda sceptical about this particular thing. I think it can be made viable but I have a strong feeling that it won't be hard to reproduce that - I was able to bake something similar in a day with Claude.