I did not get a strong answer either way as to whether the population of Deshret is literate after reading the lore. This is especially true given the emphasis on symbology.
It seems to me that even with advanced technology (or perhaps because of) all could be communicated directly. Either through schematics, pictures, or directly into the mind of a breaker. It would also support the ongoing suppression of information.
Are most people literate in Deshret? Is it restricted?
Our language code kind of represents this: there is an universal written and speaken language called Shinar, which I’d say is pretty basic. It’s not meant to be a representative of any IRL language; instead I’d say it’d be based on glyhps and symbols like early human writing more than anything else.
There are more sophisticated languages like Harran and Nisabic which is the official administrative and religious language of Deshret. Those are rare to come by; learned only by people whose job it is, and some people make a living being translators of Nisabic (the official bureacratic and administrative language) to interpret and cut deals between the Guilds, Houses and Suburban organizations (who would not speak Nisabic).