Done some investigations on “trees and leaves”, since the question was raised…
It seems, at least in my Github build, its partially working.
The “overshadowing” is dependent on the distance to the next surface:
Very visible here, the wrong color of the “shadow”, given the surrounding environment color, which is green - on certain distances it simply doesnt “get through” → turns black instead.
This would also explain why the bushes in my above screenshots are mostly fine, while the trees are not - because the trees are in that “deadzone” for Lumen, it seems, due to the distance between the planes the material is on.
In trees, this obviously becomes an issue quickly, given the distances between planes:
I hope this helps to visualize the translucency improvements and remaining issues.