This seems like an uncharitable take, the set of axioms and definitions used doesn't really fall under "mathematical truths", it's about agreement on what is implied by a given set of axioms. Even on Earth many people work in alternatives to ZFC and generally don't really disagree about what is "true".
Yet "what is implied by a given set of axioms" is the most common definition of "what's true" in mathematics. Therefore, an alien culture using completely different axioms and rules could arrive to an extremely alien math.
There might be some parts of it that are translatable to our own systems, but there's no guarantee that both systems will be ultimately compatible.
