Very unusual choices!
The words defeasible (annulled) and incongruos (not reasonable) don't fit!
The words prolix (unduly long or wordy) or sententious (terse or short) are possible.
I would choose the word, prolix if the cover of the book APPEARS to promise a long and wordy read.
The book appears to be very long and wordy (prolix) when you read its outer jacket and the back cover, but as you read it, you find that there is very little substance as it is far removed from practicality.
I think words such as discerning, astute and profound might fit better.
Hope this helps