I can’t speak to some of the other emulation packs out there (like @stefan.chirila and his Custom Chrome packs).
These were generally a combination of manually tweaking and fiddling in an iterative process and sometimes using a starting point from others works. I’ve written about it before and based some things on work like Petteri Sulonen did initially with his portra-esque, velvia-esque, provia-esque, etc. curves.
This was usually less a rigorous application of parameters (as you’ve mentioned - color checkers + specific temperature lights, etc) and more of attempting to replicate a feeling for general tones as they applied to subjects. Portra does wonderful things for skin tones for instance, but I don’t really recall testing anything on other subjects when playing.
Some of those CLUTs were likely also reverse-generated from other color curve packages and there was some work in the G’MIC package by authors far more proficient than me.
That is to say, the process is usually less about color accuracy and more about a subjective tweaking to arrive at something that might feel similar in results - pick how far down the rabbit hole you want to travel. (Some folks are happy just crushing and lifting blacks to get a print feeling - others might go farther… 
). Indeed these are, by nature, crude attempts at replication and certainly fodder for causing the color scientists eyes to twitch and to trigger them (please don’t poke or trigger any of the color scientists - they can be… ornery sometimes).
In the end I think it’d be a fun exercise to shoot again in a controlled environment with solid references to re-visit the replication but I just don’t have the time (or energy?) these days to tackle something like this. If you wanted to, I’m willing to purchase some color targets and ship them over to you. 
(Actually, this goes for anyone that might be interested).
As far as vouching for validity or approximation of any of the results - I’d say no - I’m doubtful these would be identical at all. I do think they produce a pleasing result that would trigger some memory of how I saw them once upon a time…
(Sorry this wasn’t a more solid answer than you might have been hoping for.)