Okay, I see where you’re coming from, but when you say:
… it sounds more like its other meaning of unsophisticated not an earlier stage of development. Might be better off calling it “basic” or “fundamental” instead. It’s not that it can’t be used like that in English… take primitive function (its: “primitiva”) in calculus for example, but more likely you’ll find it called antiderivative (ita: “antiderivata”) instead.
The shadow system is “just” (etymologically 
) an extension of the 3-digit major system to include face cards… if you have 000 - 999 available, the double-cards A - 10 for all suits are covered. @LociInTheSky is even pointing out in his post how he wanted to have an extension of the major system rather than 16 different vowels as you’d find in @Zoomy’s Ben system.
I’ve never seen one with 1,000 actions actually, most turn out to be 3-digit P, 2-digit A, and 3-digit O.
Dunno about that one… I can tell you that Chinese is using rhyming, so it’s a bit different anyways. I had a look at it, but my Chinese is not on a level to use it as a system. In Singapore it’s either Chinese or English and in Mongolia a lot of competitors use PAO as well… can’t speak much for the rest of the countries.
Like I said… doesn’t look that “primitive” to me…