Glad you like the game.
Regarding the book errand there have been some inquiries. I checked the code, could not yet find any strange effects.
I might also have described it badly in game what to do.
Once Irith rejects the BJ with the "You invented that" line (comes up from 12+ SLU, once you do a "finish face" move), the condition to find the book is met.
Search directly after or any other day after that in your bedroom. It will come up with 100% probability. If for some odd reason it doesn't, you can add the item to the inventory using the console (CTRL-O) with GAME.mc.addItem("ITMNovelEro").
Caps , quotes and brackets matter.
If you never have used the console, google it quickly, takes all but 1 min to make the edit in the renpy game files and 5 min to unpack the renpy files with "unren.bat" (google that too, comes up with good explanation of F95 zone)
In any case, I will make the book non-unique or craftable as well in future versions to avoid such a deadlock.