No, by "extrapolate" I mean to learn a pattern in the training data and then apply that pattern (in a useful way) to a problem outside the domain of the training data. An AI that cannot extrapolate would only be able to do the specific things that it had been taught to do, whereas an AI that can extrapolate is capable of solving new problems.

As for the language, I suspect that it is clear to the AI itself. During their training, programming AIs communicate with other programming AIs more than they do with humans, so they develop their own dialect of sorts which is good for exchanging information among themselves. This is just conjecture on my part, but my evidence is that if the AI really was internally confused about those math problems, it wouldn't have been able to solve them.