Was it ever talked about in the novels of the science behind hyperspace travel
Nope. In fairness, few sci-fi franchises delve into the depths of their FTL systems, for the simple reason that they are all fantasy: warp drive, hyperdrive, wormhole travel, quantum gates... as far as modern science is concerned, they may as well be alchemy 500 years ago. Some of the ideas
sort of fit into either relativity or quantum mechanics, but for the most part they are simply plot devices, intended to move our protagonists from point A to point B so they can meet the antagonist at point C at the right time. So far as modern science is concerned, Star Wars hyperdrives are magic. Warp drives as presented in Star Trek are equally magical, and though the Alcubierre Drive makes a noble attempt at making them simply hypothetical such a drive still is reliant upon the hypothetical discovery of types of matter that may well not exist. The Expanse's Epstein drive is probably the most realistic "sci-fi engine" in modern sci-fi, but that's because it doesn't allow for FTL travel, it simply allows sublight travel to be done at economically-sustainable acceleration rates via a hyper-efficient ion engine (ion engines are already a real thing, though they are nowhere near Epstein-levels of efficiency).
Star Wars has always been high fantasy in space rather than hard sci-fi. Expecting it to live up to the demands of hard sci-fi series is a recipe for disappointment IMO.