Several customization Options for worldgen dont seem to Impact anything.
For instance Aloe, Asparagus and Radishes spawn regardless of the amount set.
Another Thing is Generation of several other entities, such as jungle ferns, canopy vines, trees, etc, do not get impacted unless set to "None"
This can also be proven by running c_countprefabs("prefab") in both a world with one of the above set to Default and another world with them set to "less" and comparing the numbers.
Create a world with one of the mentioned prefabs set to "Default" and another set to "less". After running c_countprefabs("prefab_that_gets_tested") on both Worlds and comparing the numbers it should be clear this is an issue.