Brilliant work. Your color system is gorgeous, not to worry! I'm thrilled to discover all the different colors of outlines (no black!), and it's very inspiring! A beautiful, well-conceived illustration, lovely figure-work, and a super-riot of intriguing greenery! Bravo!
Mm, you're right... the palette does feel a bit off :/ Most of all though, I feel that the bright leaves on the right sort of scatter the composition as they're about as bright in value as the people on the left.
I guess that's why I like it. It does something very uncomfortable with the image. And not in that "oh dear they don't know what they're doing" kind of way, more of the "man, look at them getting away with that" sort of way.
I really love it. Is it the yellow/blue thing that puts you off? I know it's an cliche color scheme, but then there are lots of them since basic colors are limited. I think it works rather well in this image, though.