I need help please! I have a cake that is going to have chocolate ganache filling made with non-dairy flavored creamer. Then i'm covering the cake in white fondant and doing details in black royal. Is it ok to put the cake until delivery in the fridge without the black royal bleeding into the white fondant? I'm worried about the black royal bleeding into the white fondant once the cake starts to sweat a little when I take it out. I'll also be putting sugar pearls on the cake. do you think those will bleed too?
another question- how do you make black royal without using too much icing color?

You don't need to put the cake in the fridge. The non dairy creamer covered with fondant is good out side, for one night, and the next day.
The royal might bleed, you are right about that, and the pearls might loose their shine.
About the black royal, you can put a little powder chocolate (cacao) on the mix, but I usually use the black color right in to the white royal. Americolor is very good brand and you don't need too much to get a good intensity

so do you think i should decorate with black buttercream instead?

No, Royal gives you a cleaner finish, just don't put the cake in the fridge after is covered with fondant. It doesn't need it