I think you'd be better off restricting the stock [Genre] to a one-value per file attribute. If you prefer to use a multiple-values per file value, use a custom list field (and that can be an artist- or album-related field). Either way, you'll also find it more versatile to save different kinds of attributes in different fields. For example, if 'classical' is a genre, then 'opera' is something else. (I call it a [Style]. There may be a better terms, but that's sufficiently vague it works for the full range of music genres.) Again, that something else could be a single- or multiple-value field, and be Artist- or Album-related (or not).
When structured this way, the data is easier to maintain, allows for more specific filtering of files, and you can still display or use the data together as lists or formatted strings using expressions. That might be '[Genre]\[Style]&DataType=[List]' for a nested list in a pane, or '[Genre]: Replace([Styles], ;, / • )' for an info panel (e.g., 'Classical: Opera • Symphony').