If you check on wiki between The hunt registry, evolith and evoliths pages (yay for not updating all of them when new ones found) all but 1 mob has had it's evolith found.
There are several element/shape combinations that should exist that aren't there either but who knows maybe just won't have certain combos right...? Now that be said on the small number of equipment that we have found that can be etched, there are supposedly shapes that can be etched that have no corresponding evolith in the game.
For example Down filled triangle which means ws related there are no dark, wind, ice, water, earth element evoliths. For Filled diamond which is also ws related there are no Fire, water, ice, earth element evoliths. For the double circle one there is only light element and 2hr ones for that. There are no down open triangle, open diamonds, open or closed square or circle shaped evoliths.
However there according to wiki Tiger Jerkin can be outfitted with Down filled triangle wind.
Also there as just ones that don't make sense. For example Staurobow and some other xbows that sams can't use are dark filled diamond and the only ones to have that so far. But the only evoliths for that are +skillchain dmg on scythe/gkt.
And then there is the incompleteness of certain ones. Like how only 2 skillchain weapon types get +skillchain dmg only like 5 get +att etc...
I'm not even getting into the fact that they more or less mostly fail just how they don't really work/mesh. So is this just a joke or did they really kinda half put this together?