I see the list of tuple response type in the Example section in the instructions:
Example:
convertFracs [(1, 2), (1, 3), (1, 4)] shouldBe [(6, 12), (4, 12), (3, 12)]

This example is not said to be specific to Python: the kata contains 34 languages.

For Python, the instructions indicate the return type should be a list of tuples.

Where do you see that?

Also the name of the function is different in the instructions (convertFracs) versus the tests (convert_fracts).

Both names are accepted. See "Sample Tests" with "try:" block.