Thanks for the sample xml.
Indeed, our XUnit report parser expects some attributes which are not present in your file (the error message is not helpful at all and we should change that).
Adding the missing attributes would be possible but I think the real problem you face is deeper. When importing the test results, we have to match the test cases of the report against project test files. However, test reports usually give class names instead of test files. Our current implementation tries to match test files based on how nose behaves. That may work for other testing frameworks, but we don’t try to cover all testing frameworks.
One possible workaround for you would be to use SonarQube generic format for test reports. As it’s also an XML format, you may try to setup an XSL transformation.