I doubt that the sadhana for the Nechung oracle spirits has been translated, if that's what you mean; it is practiced in a very limited circle.
. I assume your friend's "thesis" is undergraduate, or he would have to learn Tibetan. If he has not read Nebesky Wojkowitz's chapter in "Oracles and Demons of Tibet", and Johm Avedon's in "In Exile from the Land of Snows", those would be of interest.
"Proof" of the oracle spirit's being enlightened (better to say "beyond the world" or "not beyond the world")is not likely to be available,as there are conflicting views on the subject.