I once had an idea for tag backup by creating zero-bytes copies of each file and using copy/paste [Ctrl+C] and [Ctrl+V] to backup the tags from the original files to the mirrored files.
Mp3tag's export feature can create the mirror for you; for example with an export configuration like
$loop(%_filename_ext%)echo > "%_folderpath_rel%%_filename_ext%"
After export, copy the file make_mirror.txt to your backup directory, rename make_mirror.txt to make_mirror.cmd (which I've omitted in the export configuration for safety purposes), and execute that file.
Copying tags to empty files only works with MP3 and ID3v2. Other file types may give error messages.
P.S. There is also always the option to use a Backup application to backup your audio files. 500GB drives are not very expensive at the moment.