[Jane Kong]

OK, did you try the Canon MXF plug in? This is free and it was developed by Canon itself. And for detailed workflow, here is a blog I found for you https://mattdavis.pro/2014/03/07/mxf-to-fcpx-not-working-a-possible-fix/
As I saw in your description that you recorded your videos with mic, and there are more than one audio tracks in your video. If you use Handbrake that may mess all your audio together. If this Canon MXF plug in didn’t work, then try to find yourself a third-party converter app, which has the function to seperate your audio trakcs. Here I suggest you mxf multimixer. You can just google it . It has the output format as “Multi-track video’, you can keep all or choose some of your audio channels as you want. Good luck with that !