But at that point you have full AGI and its not just today's models. Today's models still need humans to understand things since it builds upon human knowledge.

When you have full AGI of course you no longer need humans to understand math.

> Imagine if humans couldn't understand multivariable calculus, but we had access to an AI system that developed it

Developing multivariable calculus requires much more than just solving problems though, it requires defining an entirely new system and space. That is not the situation mathematicians face today, modern AI cannot do that.

When talking about mathematicians and AI don't use fictive examples, we can look at what AI can do today and extrapolate that they can do more of that tomorrow, that is what we have to work with.

In the case you posit where AGI exists there is no reason to even discuss what is left for humans to do, since AGI is defined as when humans are no longer needed for anything, the AGI can do every bit of thinking humans can.