IMHO, we need programming (formal) metalanguage, not just another language. Something in which can express e.g. an architectural discussion with LLM.

Natural languages are not logically sound, because meaning of words can shift. We need to express ideas about programs, desired properties, and specification in a language that is semantically sound and thus gives consistent solutions to consistent requirements.

Of course, the metalanguage can have the same foundation as the programming language itself. It could be expressed in Lean for instance.

What is needed is to build a library of abstractions in the metalanguage that are similar to words understood by an LLM, but in a logically consistent manner.