The darktable/Spektrafilm workflow is rather tedious, so I really understand the wish for a Spektrafilm style module in darktable. It’s currently my greatest wish for darktable too. 
This module (or other new modules) would ideally also bring support for other film properties like halation and better grain. The monochrome only grain of the grain module will not do (as I see it). If this is done as an update to the grain module, we also have the problem with module order. Grain should come after upscaling, which darktable currently doesn’t support.
I remember @hanatos saying that implementing Spektrafilm in darktable will be too slow.
An idea is to go the Resolve Film Look Creator path which doesn’t try to simulate any specific film stock (or paper), but gives you the ability to develop new “film looks” (with grain and halation etc).
The work @Christian-B is doing with 3DCF seems related.
For me it would be the ability to do dodging and burning without having to export a new linear 32 bit image for every new adjustment I do in darktable.