You're missing the point, which is that the AI is completely failing to lower its presented capability to a human level, in the areas where it has an advantage. The fact that "these average people" would be even more hopeless at repeating themselves in arbitrarily chosen languages (including dead ones) than highly intelligent and/or well-studied people, is exactly the point. Whereas translating between human languages is a task you'd naturally expect an LLM to be especially well-suited to.