48 minutes ago, Ichinichi said:Specifically, I'm hoping to find out what these "pinch waist" coupes are properly called?
I am neither a bartender nor a glassware expert, so take my 2 cents for what it's worth. That general size/shape glass in your photo is often called a tall champagne/sherbet glass or tall sherbet/champagne or some variation. In contrast, low sherbet glasses have similarly shaped bowls but much shorter stems.
I think the "pinched waist" shape of the bowl is a characteristic of the particular glassware or crystal pattern rather than the glass type. I see the tall sherbet/champagne glasses with many different bowl shapes.
Hopefully someone can offer you more assistance with the "rules" you are seeking. I purchase vintage glassware to use for cocktails and use whatever I fancy to serve my friends, often adjusting the volume of the drink to suit the glasses.