I try to spawn a lot of small structures in a biom and it sometimes has the wrong offset or is spawned on a tree.
I think, you should add a if statement somewhere to check if the block under the structure = grass X or leaves.if its leaves, don´t spawn. if it´s grass X (not the grassblock), spawn structure at offset - 1. is it possible to add a check like this?
I also want to add a feature request here:
add filters for biom spawn selection. Something like: by temperature, only land/water , no ice/snow , or by groups: all forests, all hill biomes.