Those "few layers" sum up all of linguistics.

1. Syntax

2. Semantics

3. Pragmatics

4. Semiotics

These are the layers you need to solve.

It basically took 60 years just to crack syntax at scale, and the other layers are still fairly far away.

Saussure already pointed out these issues over a century ago, and Linguists turned ML Researchers like Stuart Russell and Paul Smolensky tried in vain to resolve this.

Furthermore, Syntax is not a solved problem yet in most languages.

Try communicating with GPT-4o in colloquial Bhojpuri, Koshur, or Dogri, let alone much less represented languages and dialects.

Linguistics is not living! Language does not capture reality! So no matter how much you solve you're no closer to AGI