Happy to help 
I am glad to see the bounds scale fixed the issue somewhat. You will want to be careful not to increase the bounds too much, or you will see a drop in performance. The next thing you can do is to increase the number of cascades within the Cascaded Shadow Maps section. This allows you to modify the number of shadow cascades, the shadow resolution, and their relative distances in transition from Static to Dynamic shadows.
For more information about Cascaded Shadow Maps you can take a look at our documentation provided below.
Cascaded Shadow Maps - Dynamic Scene Shadows
Another technique you can try is Ray Traced Distance Field Soft Shadowing. There is an important limitation to this approach that requires you do not aggressively scale things non-uniformly. What I mean by this is, you mention you are scaling all of your objects 1,1,1 and you can get away with perhaps something like 1,2,1, but scaling too far will cause inaccurate shadowing and produce artifacts.
Ray Traced Distance Field Soft Shadows
Personally, I love this technique as it can really improve performance for large outdoor scenes with heavy foliage, but it also works well in other cases. The documentation will show you the process of enabling and using the shadowing technique, but if you are stuck and need some more assistance I will be glad to help.
Thank you,