How to organize and tag classical music

[Pastim]

There must be something I can do. Having groups work 95% of the time is not great. Is there really no possible answer?

I'm not really sure why the tracks can't be renumbered - if a disc is missing so be it, just go to the next one and number sequentially from the last track found to the next one found on the next higher disc. Still, I'm sure it's more complex than that.