Sure sure. I understand your point, and agree. Even in a fantasy setting written language is an important aspect of cultural advancement. Dwarfs have a language, and it has umlauts, so I expect that they write it occasionally. But the question I was raising was do they write books, or are their written knowledge stores in stone? What feels right to more people, and what would be interesting in the game? What does a dwarfish library look like?
I can't imagine the entire industry of grinding wood and plant fibers to pulp, spreading them thin with a binding agent, drying this mixture on a flat surface, taking these dried sheets and sewing them to bound stacks, perhaps binding the stack in a tanned hide and then taking ink (another creation process, though perhaps dyes could substitute the need?), and pens (quills, what ever, at least maybe feathers would be useful for something) just for the sake of recordong their histories, records, laws, instructions, and other salient information down. Stories and fictions and poems are secondary to these basics. I can't imagine this, because they carve everything to rock already, and have the tools needed to do so.
I don't yet have a proposal for it. Stone tablets might work, but feel antiquated for the period. Stone carvings on the walls and floor already exist, but are a pain to look at (it adds clutter to an already detail-intensive screen) and are mostly pictorial. Perhaps that would be a good angle to start, though. Have engravings be written texts, either at the dwarfs' inspiration, or as an option.