This turned out really nice, the grittiness doesn't show up all to much on this end. The shading on them is executed very well, though it doesn't quite match with where the light source is from, though it holds to their form excellently. The way you did the hair is wonderful, it has texture and waviness, plus the slight green hue to it is very reminiscent of their natural orientation. I wasn't expecting the stripes to be burgundy, though it's a nice departure from what one would think and works well with the fauna aspect of nature.
You're right, the shading doesn't really match the light source. I can handwave it and say there's more light coming from elsewhere (luminescent spirits maybe?) but in all honesty the real reason is I'm still not so great at shading, but I think I'm gradually getting better.
And actually, their stripes are bioluminescent and change color with their emotions/mood, kind of like chameleons. They happen to be purplish right now because that's the color the twins' stripes glow when they're feeling relaxed and invigorated at the same time. ^^
It can be hard to improve, I got where I did because my main go-to for critique is fascinated with lighting and so I spent a lot of time on it. Your shading has been improving, I remember some of your older work where it wasn't as refined.
That is a neat aspect! Is it unique to green elves?
That came out pretty cool. Nice sharp shading contrast on their skin and the long-eared spirit friend, the differently colored highlights in their hair are fun, and I like the range of warm rich colors you are using here as well as the reddish sun-glow on the undersides of the clouds.
It might have been nice to have a little bit of a lighter or brighter green on the very edge of the lilypads near the borders, so they would stand out more against the dark blue? But it's cool either way.