The author should provide their definition of 'language'. I suspect that my definition is much broader.
In my eyes, such a subset of JSON absolutely can be a language in its own right. Indeed, I'd consider the idea of a usable computation model without a language an impossibility.
Buulding a VM is not a beginner task. You can get going if you have some basic understanding of various things, but getting anything half decent tends towards being a research project.
e.g. Scheme, Lua, etc.
AI, as it stands, screws up the basics, let alone something if this scope. It has no formal reasoning. A virtual machine is a formal reasoning engine.
Ask the LLM for examples of LLMs fucking up on simple tasks. Either it succeeds, proving the point, or fails, also proving the point.
I had both GPT-4o and llama3.1, through duck.ai, make up kscreen-doctor commands the other day. Commands that were easily formatted by simply looking at the output of kscreen-doctor --help.
(it doesn't and it's pronounced as "see-wall")