I have a couple of editors working in FCPX who Tag their source audio with the interviewee / characters name ( a Role) and these come through assigned correctly to Role-Named Nuendo tracks via AAF.
But they always appear as Mono components no matter how the editor set them … Stereo/Dual Mono etc. So Stereo Music Files will always look like dual mono in the AAF and in Nuendo . But converting them in Nuendo is a minutes work with the Track Convert commands. I think it’s best done in Nuendo by me, carefully!