What is it to be Enlightened?
I think that you have raised such an important question and some may believe that 'enlightenment' is possible and others may remain sceptical of the idea completely. Personally, I am inclined to think that it may be possible to enter into peak experiences of consciousness, but such states of numinosity may not be the exclusive right of any particular 'religion' and, there may also be a danger of people who believe that they are 'the enlightened' seeing this as some form of achievement of 'superiority'.
This may throw a question mark on any who claim to have experienced 'enlightenment.' I am partly thinking of Krishnamurti, who was believed to be a future spiritual leader, and he had to step back from this and look at the nature of such a quest, rather than being drawn into the inflated ego consciousness of spirituality. There may have been so many who stepped into a sense of knowing, and as you say, Jung recognizes the way in which it may be a journey through darkness into light, with many perils along the way, and I believe that one writer, Alice Bailey, captures this in the idea of the 'dweller on the threshold'. Enlightenment may not be a simple idea but one with complex questions about knowledge of self and the glamours surrounding this, as well as the whole nature of responsibility connected to power of knowledge. However, many may even question the idea of 'enlightenment' in itself.