Red/green myself, and personally a selection of one red and one green can work if both are bright enough. This one suffers from using a shades of both, and only both (AFAICT). IOW, again for me personally, one can use one from the red box and one from the green box and that's it. Having various shades of the two most commonly mistaken colors just ain't gonna work for a lot of people. For five items, I'd use something like red/blue/green/white/orange or even beige.
But enough bitchin', I appreciate the amount of work and the presentation (color palette not withstanding). Really good work, and I can figure it out despite difficulties with the colors. Off to pinboard.in to file this one away.