Love the game so far!
I'm so confused on what the girls' stats do though. I'm not sure if I just missed it or what, but is there anywhere I can find an explanation of what the stats do? e.g. charm, appearance, popularity
Girls statistics unlock ability to buy new upgrades for them in the upgrade menu. Also there are taken into account by other abilities, both client's abilities and other maid abilities. You can find all info about it when you unlock abilities info of clients and in upgrade menu!
There will be full fledged tutorial in the future that will tell you that in more detail at the start of the game.