Sometimes, theologians talk like theologians. There is a precision needed that sometimes requires an uncommon word. And while Jesus may not have used such a word, many rejected what he taught because it was incomprehensible to them.
Author has some clarity issues to be sure as “Light” was not a ‘consequence’.....nor did it simply 'appear' as a consequence.......it appeared as the direct work of God in response. For God, who said, "Let light shine 'out of darkness'...
I doubt the words were incomprehensible, perhaps the ideas were incomprehensible...