(Disclaimer: I have no training in or detailed understanding of these subjects. I first heard of Tarski from the Litany of Tarski, and then I Googled him.)
In his paper The Semantic Conception of Truth, Tarski says that he analyzes the claim, '"Snow is white" is true if and only if snow is white' as being expressed in two different languages. The whole claim in single quotes is expressed in a metalanguage, while "snow is white" is in another language.
For Tarski's proof to succeed, it is (if I understood him correctly) both necessary and sufficient for the metalanguage to be logically richer than the other language in certain ways. What these ways are... (read more)
I'm not sure that analogy can be extended to our cognitive processes, since we know for a fact that: 1. We talk about many things, such as free will, whose existence is controversial at best, and 2. Most of the processes causally leading to verbal expression are preconscious. There is no physical cause preventing us from talking about perceptions that our verbal mechanisms don't have direct causal access to for reasons that are similar to the reasons that we talk about free will.
Why must A cause C for C to be able to accurately refer to A? Correlation through indirect causation could be good enough for everyday purposes. I mean, you may think the coincidence is too perfect that we usually happen to experience whatever it is we talk about, but is it true that we can always talk about whatever we experience? (This is an informal argument at best, but I'm hoping it will contradict one of your preconceptions.)