I'd actually guess denim is probably denim. Leia certainly appears to be wearing jeans in RotJ, and since we have humans, ducks, roses, and bees (which are at least sometimes called bees), I don't really see any good reason why in the great variety of the GFFA there shouldn't be a plant so close to cotton that the differences collapse rather than the similarities. You could call it blue serge or something, perhaps, if it bothers you that the word "denim" may come from the Earth (French) city Nimes. "Jeans" and "dungarees" evidently both come from city-names as well. Then again, so does copper (among other elements) and I'm not likely to try to change their names if they come up! A syringe, if you mean the type used to give an injection, may or may not be a hypospray. I keep thinking that's Star Trek, but I've seen it in other science fiction and I suspect it may have wandered into Star Wars as well. You could probably just as well use syringe if it's any other variety, though. For the record, I'm inclined to think that transparisteel is more for construction and things like starship windows -- there's certainly plenty of sand in the GFFA, and I think it would require more explanation to claim nobody had ever made it into glass than to say they had!