So far, I have two additional considerations for he standard.
name: license (Can be a link or symbol [CC])
type: text
name: about (Any text the user wants to add about the music)
type: text
Adding about may not be needed, but will surely be a requested feature, so having it from the start may be wise. All fields are optional, so no real harm adding it.
Licensing, and adopting a standard way of abbreviating licenses may help any future Dapp sort music by this (and cXc too). cXc.world can add this based on the user's selection and also give the option to past a URL.
Also added License