You may be out of luck because it’s a brand new camera with software that’s 2 or 3 versions behind.
What version of QuickTime do you have installed on your computer?
If you want to process the entire track, then you do need to render it, bring it into your audio editor, work on it, save it and bring it back into Vegas.
If you have more than one audio track, make sure to solo it first before rendering.
Look for the backup veg file for this project. It should be in the same folder as your veg file and will have a .bak extension on it (i.e. myvideo.veg.bak).
Copy that file to a different folder, change the name by deleting the .bak extension and try opening it that way.
If this does work, save it immediately under a new name before doing anything else.
An sfk file is what’s used by Vegas to draw the audio waveform on your timeline.
I have no idea why this one is preceded by the mp3 extension. Maybe it’s a leftover from a previous render.