Check out this free program:
https://www.mediahuman.com/lyrics-finder/I’ve been using it for several years and it works fantastic. It is kept up-to-date (May 2020 most recent), and a super simple interface. Just drag a track, an album, or your entire music collection onto the program and it begins searching numerous lyrics sites. Typically finds a full album of songs in about 10 seconds. You can also use the
add track or
add folder buttons under the title bar, but I personally find it easier just to drag files from MC directly onto Lyrics Finder.
After it has finished searching, be sure to click the tiny clipboard icon in the bottom status bar. This writes the lyrics to file tags. Until that point no changes are made. After that, be sure to run the update library from tags command (only for the files you found lyrics for).
If you already have lyrics for a given track, it will ignore it and simply show your current lyrics, so no potential for overwriting good lyrics with bad (though I recommend you test that with a few tracks first to make sure it behaves the same for you).