In the Narada Bhakti Sutras it is mentioned that the name of the guru to Narada was Sanat Kumara (“eternally young” in Sanskrit). I was a lot into New Age movement in the past with Theosophical view about Ascended Masters. Sanat Kumara was presented as a master from Venus (!). LOL. Interesting to see this name again.
What do you know about Sanat Kumara through scriptures of Vedanta? He was a rishi?
I don’t know anything about Sanat Kumara. Like you, I recall hearing the name in the context of Blavatsky’s panorama of Ascended Masters, but that’s about it.
Given his presentation as the guru of Narada, he most likely was a rishi. The symbolic meaning of his name reflects the eternal nature of the self.
Vedanta is not much interested in personages. The rishis are mentioned by name is the scriptures, usually in terms of being honored by their students for having been the vehicle for passing on the teachings. But it is the teachings themselves that are considered important. The teachings are apaurusheya jnanam, revealed wisdom that is not of human origin. While they have been preserved and protected by the sampradaya, the teaching tradition, no person is their source or has added anything to them. Even Adi Shankara only considered himself a link in the chain of the sampradaya. He clarified the teachings in order that their revelation of the non-dual nature of reality is understood correctly, but he did not modify the teachings in any way or to any degree.
In short, Vedanta pays utmost respect to the teachers who serve as vehicles for self-knowledge, but pays no tribute to any particular personage.
All the best,