Even people at McKinsey are human! They cook with water, their shit stinks and sometimes they mess up. Their not some deity that you are not allowed to look in the eye, where you only can speak when spoken to and one slip-up is an automatic beheading.
(Sorry that I am turning this into a bit of a ridicule, but I am always shaking my head at the fear and awe that speaks from so many questions here...)
Why shouldn't you call her? You have a genuine question, you have reached out to her through other channels to no avail, of course you call her! It's part of her job to facilitate your interview. It's not like your application is doomed because you dared to call someone...
So pick up the phone, call her.