Smooth

Pretty sure they are not, but you can spawn mobs into the structure manually before exporting it. They should then always generate in the structure. Be warned though, if you...

Try copying the structure files from within the reccomplex .jar and put them in your minecraft/structures/inactive folder. This seems to work for me.

This usually happens because when you set a structure to only have one possible rotation, this limits the possible places it could generate in the village, making it naturally rarer....

I had this problem and managed to fix it by breaking and re-placing the HV Transformers, so try that if you didn't already.

~~It would be nice to be able to configure the list of 'flowers' melon, netherwart and mushroom golems can plant. Also, the potion effects the Librarian and Lapis golems can...