Very interesting. I never knew he was that fluent with English.
From what I have read of his writings and transcribed interviews, I believe LTN Rinpoche gives the clearest explanations of trekcho practice that I've seen in English. The section on meditation in Bonpo Dzogchen Teachings could not be clearer, especially with regards to non-modification.
Yes, Lopon Lak can explain in English. He also realy does know the term awareness and knowledge very well, as well in English, Tibetan and Zhang Zhung languages.
Indeed his explanations about Trekchod and Thogal are very profound and clear.
There are many students, including ego, who have had many teachers, but many could understand it (Dzogchen), after Lopon Lak's elucidations / explanations.