Not every type of building can generate in a village e.g the large plains library never spawns in plains villages but only the other library variation generates. I have been going to hundreds of different plains villages on many different seeds and have never found a large plains library or some of the other houses that generate.
(I did end up finding a plains fisher cottage generate naturally but it is the only one I have ever found out of hundreds of different plains villages I have come across)
seed for plains fisher cottage: -8147983463685324578 (it's at spawn)
But this issue and
MC-147989 are still relevant