OK - well that failed - but I think this may be a bug in Natron. Since I don't know enough to be 100% certain, I've made a sample comp up with viewer at every stage:
You'll need to put an image or video on the input of course - but what's interesting is that the output is notable different from the input: but it should not be.
The problems start as soon as you put the colour lookup nodes in the script - even without making any adjustments (so the node should just pass through) looking at the histogram and output seems to confirm this.
I am, therefore, unable to make any meaningful adjustments but I'm reticent to go crying "bug" in case I'm just missing something blindingly obvious.