One way in which we're approaching the stress of interviews is to strip away the bad outcomes and allow people to approach interviews as "there is nothing to lose". Another way is experimenting with different types of interviews such as group interviews or project based interviews. Sometimes the issue with those experiments though is that they're even harder to standardize.
I think that in addition to what you said, we need to get to a measurable level of improvement. We try to measure the repeatability of our sessions in two ways: 1) when the same session is evaluated by two different interviewers, the ratings across dimensions should be equivalent and 2) (this one is harder to experiment control) when the same person does two interviews, they should be evaluated equivalently on the intersection of sets of things that were evaluated. By optimizing for these two ways of repeatability, we are hopefully going to move toward much more objective driven evaluations that capture the engineer's understanding of different areas and not just the spur of the moment.