Ah, you hit on a thing I realized in reworking my histogram: making decisions in raw processing doesn’t require the sort of fidelity you get in a tool like Histogramerr or RawDigger, at least I don’t. Really, I need to know the bounds and topology as I described to make tone decisions. Now, color actually requires a third regard, that being the channel relationships. I’ve put such to work in both white balance and color negative conversion to good results, determining shifts in the individual channels as evidence of a color cast.
I may yet write a separate raw histogram tool. But, due to the internals of rawproc and the distinct considerations of analysis, it would be that, a separate tool.