"@Operalala — I can see from your questions that you still have misapprehensions that will only be dispelled once you see the system up and running."
Well, yes, I have misapprehensions that Vocalists' needs will be met in any way.
One thing we all learn in life is to take with a big grain of salt statements like "just wait till you see it", in place of addressing concerns. From everything I see, when "I see it" there will be no distinction between the major song types, except for those specific languages that happen to have a term on the list, Operettas will be mixed with Opera, which in turn will be lumped with Ballets, and I have yet to see explained anywhere how cross-category tags will fit into the category tree.
"1. Compromises are necessary for technical or other reasons"
Yes, this system, as we see it now, is quite gimped for Vocalists, and there aren't any technical or other reasons for this.
"2. Implementation cost outweighs utility"
If implementation lacks utility, we will find ourselves going back and re-doing things. Or even worse, leaving things very user-unfriendly.
"3. People simply can't agree philosophically, no matter how well informed"
Some things can actually be pretty clear, such as the fact that, in musical terms, Operas and Ballets are quite distinct.
"4. Prolongation of argumentation is detrimental to the morale of everyone involved (i.e. too much energy wasted on too little return)"
I don't think anyone needs to spell out their morale at seeing their well-founded concerns called "argumentation", or having their good judgement dismissed.