The current online database is a redirect from FreeDB (
http://www.freedb.org/). This is a user input database of all types of CDs including CDGs. So it is only as accurate as the users inout to it.
I do know that MTU has been negotiating with a couple of companies that keep these kinds of lists to try to get a more accurate and current database, but I don't know what the status of that is. Admin would have to provide any additional info.