
Let me flesh out my ideas of why Gehn failed as a writer (which he really didn't but....). Gehn had a focused, brilliant, but sick mind. I believe that Gehn was more than able to write brilliant ages, but that his anger, frustration, and violence clouded his abilities to write. In the book of Atrus it says that he learned from reading books he found in the cavern, iirc, they never said if these were linking books, descriptive books, or books on the use of the art. Since the trilogy books are not really canon anyway, that leaves the idea of what Gehn found and how he used it wide open. So yes, I think it is entirely possible that explorers or the DRC could find learning books on the skill of ink creation, book building, and writing of ages.
However, if we want to have a specific way that we did learn to write, we'll need input from Cyan. Nothing more than RAWA posting, "Yes, it is entirely possible someone could happen upon materials that were for teaching students in the ancient GOW how to create descriptive and linking books.".
From a starting point like that, I believe, we would need no more from Cyan.
I still think a character or explorer should be used to start the use of the name Guild of Writers. Perhaps they started it as a way to give explorers a sign of who to ask about writing? I wear a GOW shirt whenever I am in MOULa and the conversation usually turns to new explorer made ages. I think that we wear the shirt to show we are a person to ask about age writing, and to inspire others to give it a try.