Even with MC-140759 fixed and with all the new Structures from Villages not missing a connecting Jigsaw Block it seems like Village Generation is in front of another unknow Bug that from my experience doesn't share a Pattern to determinate the cause of said Problem.
At the beginning I thought it was due to some incorrect names in the Structure Files as it seems like names accross Village Structures from different Biomes are not sharing the same Technical name, for example the Fisher Cottages, currently all of them have a different name and 3 of 5 Fisher Cottages are not generating naturally anymore:

Incorrect name in the Structure Files, previously it seems like this didn't happen since the valid name for this Structure was for example a Taiga Fisher Cottage:

taiga_fisher_cottage_1.nbt

But at some point it got changed to only accept the name of the Structure as "Fisher" or "Fisher_Cottage" without the number 1, for example, the only Biomes where you will find Fisher Cottage generating naturally is on Desert and Snowy Tundra Biomes, this because the Fisher Cottage for Desert Village is saved with this name:

desert_fisher_1.nbt

And the Fisher Cottage for Snowy Tundra is saved with a different name from the Desert Villages, but still can generate naturally without any problem, my guess is that the missing number 1 at the end (Something that the other Structures has on their name) still valid and let the Fisher Cottage generate on Snowy Villages:

snowy_fisher_cottage.nbt

And now I will display how the rest of the other Fisher Cottage Structures are saved and why are not generating naturally anymore:

taiga_fisher_cottage_1.nbt

savanna_fisher_cottage_1.nbt

plains_fisher_cottage_1.nbt

Solution for this, will be, save the Structures only with the "Fisher" name or match it with the Snowy Fisher Cottage by deleting the number 1 at the end of the name to let these Structures generate naturally again.

That was in fact my guess for this Issue, but after a lot, and lot of deep testing I found out not only Fisher Cottages are failing to generate naturally in some Villages, after check on

MC-147742 I also realized the absence of the Plains Library #1.

plains_library_1.nbt

And the weird thing is that this Structure doesn't have an incorrect or different name from another Biome, (Ex: savanna_library_1.nbt).
And even the Library #2 (plains_library_2.nbt) which has a different number from the rest of Libraries accross the other Biomes can generate without any problem, meaning that the name is not a problem here in this Issue.
The only thing I can add is that it was possible before to find these Structures in previous Snapshots when they were first introduced.

I will list all the Structures that I cannot find naturally on Villages, I also want to ask any Feedback on this Issue since it's very hard to keep track on this.

I might be wrong and put an incorrect Structure that actually generates or I might forget about add one, anything is welcome so please let me know and I will try to Update this Issue as soon as Possible.

Keep in mind that to participate in the Feedback you need to be playing the most recent Pre-Release, because previously it was possible to find all these Structures when they were first introduced.

Plains Village

plains_library_1.nbt

plains_fisher_cottage_1.nbt After visit more than 24 Villages it was possible to find a single Fisher Cottage on Plains, but it seems like the generation it's very, very rare, I think is even impossible to find more than 1 of these Structures in a Village.

well_bottom.nbt

plains_small_house_8.nbt It was possible to find this Structure, but compared to other Small Houses it was very rare to find.

Savanna Village

savanna_shepherd_1.nbt

savanna_fisher_cottage_1.nbt

savanna_temple_1.nbt

savanna_small_farm.nbt

savanna_large_farm_2.nbt

Snowy Village

snowy_shepherds_house_1.nbt

snowy_small_house_4.nbt

snowy_medium_house_3.nbt

Taiga Village

taiga_fisher_cottage_1.nbt

Desert Village

desert_large_farm_1.nbt