I would be super interested in theory! I say in theory because, well, new experimental things are interesting but it’s hard to do them well.
In particular there are some design challenges in combining preset narrative and procgen stuff. Procgen stuff is often designed to maximize replay value–it’s new every time in some ways, and you also become gradually familiar with the systems, but you never have to repeat yourself exactly.
Handcrafted narrative does not reward replay in the same way. It’s the same thing over and over again. So there’s a potential for a mismatch here–if the narrative is lots more interesting than the procedural part, people will play it through once and miss the new experience every time. If the procedural stuff is the really interesting part, people will potentially get tired of the narrative parts every time they replay–like a big cutscene.
So it’s important to think carefully about what you want out of the procedurally generated stuff and how it fits into the game! One thing I found in a non-text game was an exploration game where the randomization meant you had to explore for real, instead of learning where everything was for subsequent playthroughs.
OTOH the way you describe things with the manual sections at the beginning and end could work–it might be like nethack where some key stages, including the end, are preset maps (or chosen from a few possibilities). Then the prewritten parts are kind of a reward for victory–though you’d also have to make an entire interesting procedurally generated game, which is very tough!
Some things worth looking at would be Rogue of the Multiverse, which has a very strong narrative with some randomized sections. (I think the consensus is that nobody replays it to get more of the randomized parts.) ADOM is a classic roguelike (not a text adventure) with a strong narrative, as I understand–I’ve never played it much partly because I barely play standard roguelikes that aren’t Brogue anymore. Joey Jones’ and Mevlin Rangasamy’s Calm maybe doesn’t have procedural generation per se but it seems to me like it has a lot of that kind of flavor mixed with narrative? You might also check out Flexible Survival, which is a mind-bogglingly ambitious RPG done in Inform (I should also mention that it is an extremely explicit postapocalyptic furry pornography game). There’s also Legerdemain which is a game in a roguelike style with preset maps and a very strong narrative–at least I think it has a very strong narrative, I never got that far in it.
Another thing you can do is have some procgen stuff that provides flavor in an otherwise conventional IF game. Chris Conley’s room in Cragne Manor is a great example of that. (Runs away cackling before you figure out how long it takes to get to Chris Conley’s room in Cragne Manor.)