Just an FYI the semicolon is a display and entry contrivance / shortcut. If you look in the tag inspector, there are actually multiple GENRE tags for files, not one separated by anything.
I use PowerAmp, and PowerAmp does read the multiple genre tags. It splits them out into individual genres in your library displays them in tags with a colon.
In reality, though, these are both ways to display what are actually multiple genre tags in one line.