There is literally no reason not to. The idea that in two and a half millenia of living and fighting side by side literally no scholar ever thought to ask is frankly ludicrious. And unlike for many other reasons, they would not get a grumbling and silence because there is no reason whatsoever to not explain.
The question is not "would anyone know, ever"
The question is how many (never said there were none) people know. Yeah, scholars have probably found the knowledge, and the occassional Dawi focused diplomat too. But even if they wrote it down, how many people have read the book, considering how rare books are, Mathilde's obsession nonwithstanding? Heck, even if one is a Dawi scholar, what diferentiates Dawiologist 1 who has the correct information written down, from Dawiologist 2,3 and 4 who have books that are full of misconceptions, which even Dawiologist 1's isn't completely free of?
The subleties of Karaz Ankor and how Holds are kinda sorta technicly but not really subservient to the High King is not something Dawi like to talk about, even amongst themselves, because it reminds them of how badly things have gone and how far from the "ideal" they are from.
Thane's, are not that, while most people in the empire might not be aware of the intricacies, it is not something dawi keep quiet about so a motivated scholar or a diplomat should have no real problem learning about it.
Yeah, sure, anyone motivated enough to take a trip to ask that specific question would probably know, as well as anyone who spends enough time among the Dawi. How many people are these? If we exclude the ones who decide to stay to a Karak full time and as such are only maybe citizens of the Empire in technicality, if at all, I doubt there are more than a hundred in the whole Empire, if that. Trips back there were tedious, slow and dangerous, we got lucky and solved that problem via a spell crit and later a gyrocopter, but for most this kind of thing is unacceptable.
The only guys likely to know apart from us are merchants and their guards, (and even then its a coin toss) and the occassional dedicated scholar or diplomat.
Edit: Admitedly, imperial Dawi and those that ask them probably boost these numbers.