A quick thought about assessing interpretation

I had an interesting conversation with the person I interpreted recently. After we worked together for three days and were saying goodbye, he thanked me for doing such a great job. I was of course very flattered, but I was wondering to what extent can someone who does not speak the target language assess the interpretation. He went on to explain: he knew the interpretation was competent due to the questions the participants asked. They referred to some of the subtlest aspects of his lecture and showed in-depth understanding of everything it entailed. It was a very interesting idea, to assess interpretation on the basis of the audience’s/listeners’ feedback, and I don’t mean feedback as in “do you think that intepretation was good”, but feedback as in production, associations, reflections. It makes sense.