For me it comes down to how I recall the book made me feel. I might match that to how I'm feeling in the moment, remember the book and out of nostalgia want to re-feel that recalled memory.
Book piracy is one of those topics that never seems to go away and probably never will. I get why readers sometimes turn to pirated copies, especially when books are unavailable or unaffordable in their region, but at the end of the day it can have a real impact on authors. Particularly indie...
I find the freedom and limitlessness of fictional writing to be quite enjoyable. There are no barriers and everything goes. You can start at absoluetly nothing and make something incredible.
I think if you do enough research on it, you absolutely can use it. Having to look something up doesn’t mean it doesn’t belong, as long as you understand it and it fits the context.