Typically files that are hidden and start with an underscore on Mac are similar to what would be in the recycle bin in Windows. They are placeholders for restoring the original if you choose in MacOS.
That said, I would use a filter to find as many of these as possible, and check to see if the remaining unhidden versions are valid audio files. Only if yes would I get rid of them.
Better yet, maybe after you find all of these tracks you can move them to a separate drive, then check to see afterwards if all remaining tracks play as you expect. Then you can clean up that other drive.