Small quality of life suggestion:
I like the fact that you can customize what your slaves should call you. I think it would be even better to be able to change the default for all girls at once, maybe in the options ?
For example, if playing as a futa, they will call you "Master" by default. To change it to "Mistress"(or whatever else) you have to do it for every slave separately. A way to "change for all" would save time.