Although considering how the sorceress is talking about curiosities and all that we could exchange Empire spices. Spices are almost always very valuable.
Luxuries are also good thing to trade—the Dreadlord seemed impressed by the wine she was drinking.
She takes a sip of her drink, then looks mildly surprised and gives it a curious look.
I suspect that Naggaroth has a very basic level of agriculture—mostly roots, grains, and animal feed—and that high value foods and drink come from raids and what little trade they can get.
But of all the topics we could get from them, I wouldn't trust anything in a Druuchi book on magic, specifically. We've seen evidence that their magical learning is deliberately sabotaged by Morathi, and I fully expect any magic books to have similar traps. We'd be poisoning our understanding of magic in subtle ways that aren't just dangerous, but worse - incorrect.
You're not wrong, but there's another element to consider—we can independently verify any Druchii magic, but they can't. The Sorceresses have to take Morathi's teachings in good faith, because if they don't, they'll probably be killed for treason. We, however, can compare it to the Empire's own traditions, to Teclis's teachings, to the magical knowledge of the Eonir and the Grey Lords, and potentially to Dwarven, Kislevian, Bretonnian, and Nehekaran magic.
In a vacuum, it's probably flawed. But we won't be looking at it in a vacuum—we'll be comparing it to what we already know, and we'll keep the stuff that works, and get rid of the stuff that doesn't work.
I doubt that every single spell, incantation, ritual, and technique is sabotaged. There'll just be a few key things—like the vortices—that'll prevent her students from attaining enough power to challenge her, but not enough to cripple them on the field of battle. Otherwise the Sorceresses would never win a magic duel if everything they were taught was wrong.
And arguably, it's not that different from how Teclis taught magic to the Colleges. We know Teclisian theory is wrong. We know Teclis hid things from us, and even lied to us, and it's hard to ascribe charitable justifications to him for that.
