Hiya! I know I'm waaay late to the party, but I'm the guy who did the CNI themes.
I haven't updated the themes for ages and have forgotten everything about rockbox theming (as little as it admittedly was); IIRC there was some kind of change in the syntax of the scripting language or summin like that and I never got around to dive into it. I have also lost all the source materials for the graphics. And I don't have my iPod anymore.*
If anyone is interested and likes the themes enough, please do feel free to take the reigns and bring them up to speed, as I will most likely (certainly) not update them any further. It is nice to see how often they've been downloaded and how generously they've been rated, though.
*Nowadays, I'm rocking an XDP-100R with GMMP instead of the included Music app.