When you ask "What is 2+2?", you mean a specific class of formal systems, not an "arbitrary formal system". The subject matter is fixed by the question, the truth of its answer doesn't refer to the circumstances of answering it, to situations where you decide what utterance to produce in response.

The truth might be a strategy conditional on the situation in which you answer it, one that could be correctly followed given the specific situation, but that strategy is itself fixed by the question.

For example, I might ask "What should you say when asked the value of 2+2, taking into account the possibility of being threatened by puppy's death if you say something other than 5?" The correct answer to that question is a strategy where you say "4" unless puppy's life is in danger, in which case you say "5". Note that the strategy is still fixed by the question, even though your action differs with situation in which you carry it out; your action correctly brings about the truth of the answer to the question.