Sorry, this discussion is old and it has answers, the highlights reconstruction module is broken and darktable’s devs don’t want to fix this.
Using Lab/LCh before that correction is done is conceptually wrong.
Won’t fix, we can’t change the algo without losing compatibility. Checkout filmic reconstruction.
Filmic reconstruction (it just blur the highlights and doesn’t recontruction at all)
This is a limitation of the algorithm used, not a software problem. There is nothing we can fix in the program that doesn’t require to rewrite the maths first and use a different algorithm.
I’ve posted somewhere in the forum a comparison of raw editors, darktable doesn’t render correctly raw colors (neither arwtherapee), in my comparison it adds green bias in the shadows, however looks at the strange pinkish skin and gray hair.
I suggest you to decode the raw in Photoflow, it renders correctly the raw, the highlights reconstruction works great and it support dcp profiles .