In my limited experience multiply blending mode is one option to simulate stuff like duotones that will be printed in offset printing.
Is it accurate? It is good enough for me.
Here is the catch or catches in plural...
It does not exist to my knowledge any color profiling of a random combination of direct inks, add that different inks with different transparency coefficient and paper absorption.
You are quoting a silk-based print where traditionally the inks are NOT transparent.
I am not sure about this, but I think even offset print spot inks has not the same transparency over process inks.
I have only simulated duotones because I have indeed used them "a lot" (I am pretty sure more than most designers) on low-cost magazines, and we never expect an "accurate color" we expect good design and a nice look to it.
Here is an example.
Using a duotone was to save costs, but in other cases, the cost was first cut using lower quality paper, so, we never expected color accuracy.
In your case, it is probably a good idea to invest some time in making your own tests and compare them with a printed result.
You can probably make a "profile" for example, using a duotone blending mode, and then adding an additional layer to simulate the "real" output, making it darker, or lighter or a bit unsaturated.