I'm not against adding a new name if it makes glorious sense, but we should not remove the old names from unittest as that causes unnecessary pain (based on past experience).

assertCountEqual does make sense in terms of the "equivalent to" context from the docs.  Thought I agree with you, its meaning is generally not obvious and must be looked up to be understood. https://docs.python.org/3/library/unittest.html#unittest.TestCase.assertCountEqual

assertUnorderedEqual is a reasonable name, but I don't find significantly better than assertCountEqual from a "never read the docs, just reading the code" understandability point of view.  It makes me wonder "unordered what?"

that's a vote of -0 for the status quo.