I'm having trouble understanding why you'd respond with that. Are you interpreting knowledge to mean knowledge-of-language or something?
>>>> But it does mean they're about "language" rather than knowledge.
>>> To some extent, those are kind of the same thing.
>> They are not the same thing.
> Of course they are the same thing.
Language and knowledge (both broadly construed) are obviously not the same thing. Language can encode non-knowledge like nonsense or lies, and there is knowledge (e.g. of the experience of qualia) that can't be expressed in language.
I think the point up-thread is true: something that knows only about how language is unreliable source of knowledge. Even if all its input is true knowledge, it can still blindly combine that input in linguistically plausible but false ways.
All the more and less formal models we invent for describing "language"? This is just fitting curves to a snapshot of reality. So sure, "a lie is language, which is pretty close to the opposite of knowledge" - a lie can be expressed in the formal model. But the truth (as subjectively understood) is much more likely to be spoken or written down in practice.
Communication isn't random. Language isn't random. Learning it is picking up the patterns.