I don't fully get the arguments here. I would need a few examples of where it makes sense for you to negate the shadows, and where it does not.
1. CShading_Shadows cannot be used to subtract from tonemapped images, i.e. linear workflow only
This is a general rule because of the way blending operations work (adding color values, subtracting them, etc). I don't think there is a way to overcome this.
As a workaround, you can save your post settings in a CONF file, then reset tone mapping, then compose your image in PS or other app, save to EXR, open in CIE and apply your CONF file.
Here are my thoughts...
Let's say we are rendering an image like this:
The object on the wall is casting a shadow from direct light. This is easy.
The object on the floor is casting a "shadow" from indirect light (bounced off the left wall).
If we want to get rid of the direct lighting shadows, that's easy:
Now I am trying to imagine what you would want to achieve by getting rid if the "indirect lighting shadows".
You would either end up with a fully black screen (if you would remove indirect lighting whatsoever).
Or you would end up with a fully black screen with direct lighting on top of it (if you would remove indirect lighting and keep direct lighting), which is basically the CEssential_Direct render element:
Or you would end up with something like pure diffuse color without any shading (if you would negate the indirect lighting in a similar way as the direct lighting shadows are negated, leaving only indirect lighting):
Or you would end up with something like pure diffuse color without any shading with direct lighting on top of it (if you would negate the indirect lighting in a similar way as the direct lighting shadows are negated, leaving only indirect lighting, and then you would add direct lighting on top of the result):
I don't think any of the above examples is desired. Could you maybe try "simulating" the effect you are after? For example, render an image, and do some adjustments in Photoshop to showcase what your desired end result would look like? (or just mark in red the lights / shadows that you would like to remove or adjust in some other way).