Oh, super easy answers, take your pick!
1) They won't tell you. They'll just have the books largely written by AI, send a couple editors through it to chop it into the right shape, then ship it. At least 90% of the customer base won't recognize it's AI.
2) They'll make their own AI. With D&D and Beholders. Which is to say they'll buy a LLM with Generative AI, refine it by running all the Forgotten Realms lore through it 'til it 'Memorizes it', then use it to write books while they lease it out for $10 a month to the populace to 'DM' for everyone.