Hi @3dev , thank you for your input.
I already have two post process volumes in the scene, because otherwise the exposure control is going crazy while switching between interior and exterior. But with two of them it’s fine 
I tried to configure each light source separately with disabling all the others and it helps a lot, especially with the subtle lighting. Thanks for that hint.
But for the light setup with only a SkyLight + a HDRI: I tried this within a smaller level, and after some tweaking and googling I got the shadows working. I’m using a static SkyLight, Intensity of 15 for that kind of clear daylight HDRI and with higher Lightmass settings the scene itself looks quite good. But with only one static SkyLight I’m missing the Cascade Shadows from the Direct Light and baking them isn’t an option I guess? Is the only option there to change the Light Channel for the foliage and use an additional Direct Light with Cascade Shadows only on this second channel?
Or am I missing something else?
