If we go with what the other girl said, the star constellations Kanna learned are from the Ainu culture, explaining the discrepancy with the Greek version used in astronomy in modern days.
Hoyau is a dragon-like creature.
Don’t get the forming plasma thing. But that ball and her eating it could be Kanna draining the static charge from the cloud and destabilising it, so the cloud disperse faster rather than hanging in the sky or becoming rain.
Probably a different way from how another dragon girl ends storm early by forcing it to unleash everything at once in a lightning storm.