serious generation problems when modifying vanilla structures with structures blocks

Problem :

When you change the content of a vanilla structure like a meeting_point or a street the game wont or wrong generate the village
screenshot (1.png ; 2.png) :
to do some test i have saved vanilla streets with blue wool on it (size of the structure not modified)

And you can't add your own structures to a jigsaw pool (I want to create an incredible number of new building).

Description :

Now all village i see (4 or 5) have their streets structures separated by grass blocks and don't have more than one house if they have one

P.S: The natural generation of structures are already hard and bugs aren't easy to detect because you can't know if it's you the problem. Please take time to do a lot of test like you are a player doing a datapack because replacing structures of the game are realy realy bad.