Is rang rig or rig pa the translation of this "self-awareness" term?
rang rig pa/svasamvedana means "reflexive knowing", and it is theory of cognition usually considered to have originated with Dignaga and Dharmakirti.
But is it not important in Dzogchen, even Garab Dorje's (or Patrul's comments) Three Words using it?
No, svasvamvedana is different i.e. it is rang gyis rig, self-knowing.
Rang rig in Dzogchen is rang gi rig, one's own, and is derived instread from another Sanskrit construct: atmyavedana, and in turn this is part of a long phrase, very common in Sanskrit, pratyatmyavedanajñāna or in tibetan so sor rang gi rig pa'i ye shes i.e. personally known wisdom. This is what the rang rig means in Dzogchen i.e. one's own knowledge, wisdom that was no learned from another but arises from one's own experience.
The translation of Dzogchen tantras and texts is still in its infancy, and the 95 percent of them should not be trusted by people who do not know Tibetan,including my own translations.
As is the case with much tantric literature, the root tantras of Dzogchen cannot be understood completely without commentaries.But, within the past ten years or so, six seminal commentaries on the man ngag sde tantras attributed to Vimalamitra have come to light.
Earlier translations made without recourse to these commentaries will be somewhat inaccurate automatically -- it just cannot be helped and there is no reason to blame anyone for honest efforts carried out with insufficient supporting commentaries. But it must be understood that good translations of Dzogchen texts into English are a desiderata. My own efforts are merely a preliminary. I am sure that after I am gone, they will be picked up, picked over, polished or discarded as the case may be in the quest to make clearer and more accurate translations that conform to the definitions and explanations of key points of Dzogchen teachings found in the tantras and commentaries themselves.
In addition there is a wealth commentarial material in the Vima Nyinthig that needs to be digested well.
Maybe in 10 years we will start to have fully accurate, fully nuanced transalations of Dzogchen texts that are widely available. Frankly, most Tibetan lamas do not really deeply understand these tantras and their langauge even if they understand Dzogchen in general perfectly well (moral of story: you do not have to be an expert on the 17 tantras to achieve rainbow body).
For example, today I am working on a citation from the klong drug
about nature, essence, and compassion which is literally 1.75 folios long. It is so dense, it cannot be unpacked or understood, let alone translated, without the commentary (which I have, fortunately). In this translation this long and important passage will have to be extensively foot noted with explanations from the commentary (or an appendix, since it covers some 7 long folios). Longchenpa is no help at all, since his method is to merely make a point, and then unleash a long citation from a root tantra with virtually no explanation of the meaning of the passage. In fact in his commentary which closely follows the commentary I am working on (i.e.the tshig don mdzod), he skips this passage entirely because it is so hard to understand without the commentary, or so I am convinced, because for the most part he merely follows the citations as given in this earlier work in the exact order they are presented in that latter.
Back to work...