The biggest issue is there is no real alternate vocabulary for mystic experiences.
I have mystic experienced out of my brain box.
I am so good at creating that whole 'one with the universe thing' that if I remember, I try and generate it at least once a day.
I also get it when running outdoors in beautiful locations and when I am creating something, especially with painting.
I personally think it has a lot to do with a meditative state and just being really observant and present to your environment.
It is a function of the brain, it isn't mystic or spiritual, even though it does really feel quite lovely and impressive.