I'm torturing myself with the second hearing.

I feel sorry for this Ambassador.
I believe she is an unwitting sacrificial lamb.
My premise: She has a person in her office who was specifically tasked with handling the Hunter Biden - Burisma issue. It was the Ambassador's job to work around this person let this person do the interventions.
The ambassador knew that this person existed, and that is all she knew, other than rudimentary information.