I have to admit: I don't like the approach of using only in-game texts to describe the setting. Although it is very atmospheric and delivers a very special reading experience compared to other game systems and settings, I find it hard to extract important and game relevant information. So although I really love the setting, its characters, its ideas, I don't like the actual description because as a GM who likes to make up his own campaigns and adventures the accessibility is not the best.
From role-playing games like HârnWorld or Traveller I know the concept of glossarys or lexicon style setting information. In HârnWorld it is called Hârndex (an Index of the world of Hârn), in Traveller it is called Library Data and included in the core books, while additional library data is presented in setting books and often adventure modules. Although library data is handled differently in the I guess 5-7 editions of Traveller you can buy

To my knowledge something like that doesn't exist for Shadows of Esteren. I think such a glossary, index or small dictionary/lexicon would be a great addition, especially for new players and GM's. Furthermore, English is a foreign language to me and my group. Our English skills differ widely and not everyone can read the books without trouble. A glossary with a more plain writing style - and clearly out-game - would be a great help for us. It doesn't need to contain GM knowledge (which is coming with Secrets, I suppose), "what could the average player character know on this subject" would be completely sufficient.
So I am hoping for such a product in the future.
I mean a glossary or lexicon, where there is not only a sentence in a dictionnary style to explain terms like Tri-Kazel, Varigal, Magientist or Demorthen, but maybe one or two paragraphs per entry, depending of course on the complexity of the subject. It would be meant as an addition, not as a replacement of Book 1 etc.
Maybe I have overlooked something and something like that already exists. In this case I would appreciate any pointer where to find it. Especially if something exists as fan material I will have missed it for sure.
However, maybe I am alone with my opinion and the majority of the players aren't interested in such a product, although it wouldn't do any harm, to have it. What do you think?