OK! Thanks to the super helpful whoward69, I'm now releasing CCSMM/MMR! This mod adds new luxury resources to mercantile city-states so that each CS has its own unique luxury good.
The mod has been tested and works with CCSMM and should work fine with other mods.
As of version 1, there's some transparency issues with some luxury icons, but I can work those out for future versions.
The resources added to mercantile city-states are:
Furniture
Cigars
Huitlacoche
Rooibos
Ice Wine
Henna
Orchids
Cashmere
Quetzal
Tapestries
Shih Tzu
Leather
Shea Butter
Thanks everybody, and I hope you enjoy!