Ok if i am right you want a 5 slider selective tone system which ar not blending.
The luminance layers must be not overlapping?
I understand your problem about the overlapping isuue’s when you just want some shadows in the deapest part lifted of just the bright spots lowered and the middle section gets “dull” by the lift and lowering.
Are you having Filmpack?
If so the advanged contraat sliders can help toget better results.
And by using controlpoints to make luminanced color selections you can edge or feather the overlapping area’s of the selective tone section.
I don’t be experienced with LR nor Capture one but DxOPL is about building walls with bricks not pour concrete in a hole. (By making smaller adjustments in different sections you can mold the rawfile to the wanted point. If some thing works often you can create a preset or partial preset to speed up this task.
I am not saying DxO is working easy or the best or good, just that playing around often in it makes it more easy to choose the right tools for the job.
This specific problem is solvable with the advanged sliders in contrast.
Greyed highlights are over detailed and by using the negative contrast too it helps to keep white white. Lifted shadow which is washed out can be more detailed by pushing more contrast in that part of the luminancesection.
Maybe this helps until selective tone is more your style.