Flawed Feature Generation (still raytracing from top of chunk)?

CC Version: 1.12.2-0.0.1257.0-SNAPSHOT-all
CWG Version: 1.12.2-0.0.169.0-SNAPSHOT-all

I may be mistaken, but it would appear that feature generation (trees, grass, etc) is still performed from the top of the chunk, similar to vanilla. As a result, any terrain which features frequent loops (or obstructions?) over the Y axis (i.e. cave/sky island terrain) will see that the lower sections of chunks are unpopulated. Alternatively, I could be mistaking this for another issue, but I somehow doubt greatly that grass can be this rare and inconsistent in spawning. Does a stone ceiling within the top of the chunk interrupt the spawn raytracing into grass below; such would seem so?

My preset is as follows, but for better confirmation you may wish to remove the artificially-spawned features:
cubicholeseed.txt
(There are definitely better presets to test this, only, this is where I personally discovered eccentricities in grass spawns. Trees, I could understand with the limited space, at least.)

[Niko-sk2x]

I know there are some issues around tall grass and last i tried i couldn't figure out the cause. I modified the code in a way that attempts to roughly preserve vanilla spawn frequency without iterating from the top of the world or chunk. I will look into this again when i have some time again (which may end up being in July).