PPM looses detail in shadows and highlights

We’re working on a VR project in UE 5.3, as a result of bugs and their mitigations have lost most of the post processing stack. As a workaround we’ve re-implemented tone mapping and color adjustment as a global post process volume & material.

The image below shows an almost acceptable (for us) result vs the disabled stack.

Unfortunately we’ve lost detail in the colored shadows under the spheres, and highlights from of the two areas indicated by the yellow arrows.

The following shows the material graph we’re currently using.

I’ve been reading blogs, but I’m not a particularly good colorist, as such am unsure what I need to change to make improvements in these subtle areas. (Split Tone, Curves, Levels?)

Do you have any guidance for me?