There is a slight misunderstanding about this subject of the 2 Dagpo Rinpoche's, Tagpu Pemavajra, who the author of Infinite Aeons is, and who went to Tushita and returned with the close lineage instructions on Dorje Shugden. People are confusing the following people - Dagpo Kelsang Khedrup, Dagpo Jampel Lhundrup, Tagpu Pemavajra.
Trijang Rinpoche's commentary is to the poem called Infinite Aeons, and the author of that poem is Dagpo Kelsang Khedrup, NOT Tagpu Pemavajra, and NOT Dagpo Jampel Lhundrup.
Dagpo Kelsang Khedrup was the Guru of Dagpo Jampel Lhundrup who was the Guru of Je Pabongkhapa.
Tagpu Pemavajra was the Guru of Pabongkha Rinpoche who went to Tushita and brought back the special close lineage teachings on Dorje Shugden.
There are several reasons for the misunderstanding:
1) The names sound very similar, and it is easy to mix up if there is an abbreviated reference such as 'Dagpo Rinpoche' for instance.
2) Admin of this website made a mistake in the English translation of Trijang Rinpoche's commentary to Infinite Aeons by putting a picture of Dagpo Jampel Lhundrup instead of Dagpo Kelsang Khedrup who is the actual author of Infinite Aeons.
The picture below is Dagpo Jampel Lhundrup, Pabongkha Rinpoche's Guru. He is the disciple of the author of Infinite Aeons.