By what I have seen with my own eyes along with a large group of sober people, I cannot guess if they were sentient or not. They were simply "unidentified", and impossible for any of us to explain through common physical explanations.

But a large portion of the local population, I would guess one in four, claim to have seen these things too, and the legends go back to time immemorial saying that they are spirits or the energy bodies of living witches or sorcerers.

I suspect that plasma phenomena, now documented in Norway and other specific parts of the earth could explain the phenomena best to the modern western mind, although for all we don't know maybe plasma balls can be "living" or conscious, so then the descriptions as in the old stories could have merit if that were the case.