They should create a recursive+fractal object tree with verbs for transition, in a constructed mark-up language, to generate the story.
Then implement its verbalization into a custom human language.
I believe, it won't be worse than 99% of biologically written plots and stories...
Also, the PC text quests prove that 90% of visualisation is made by the reader imagination.
So, just a customized readable thing, following the reader desires, will be readable very well, like a foreign language story in amateur translation.
To match the reader preferences, the model should read the reader's favourite stories to follow the writing style and words, which the reader prefers.
Thus, a once-generated story in mark-up language can be verbalized very differently for different readers.
(In Shakespeare style for one, in leet-speak and emojies for another one.)
They should split the story into standard basic actions, to fill the primitives with customized/random details
(Action: "%Person#1% %punch% %Person#2% with "Object%1"" → "%Person#1% %receive_object% %Object1%" %concatenate_action% %Person#1% %random_punch% {target=%Person2%, tool="%current_object%"} + %random_ornamentation%) → "Jill took the book from the table, and accurately slapped Jack's head."