In order of decreasing importance:
1) I played V1.6 until level 15, and while some were easy, some less so, level 12 (Warm) has me totally stumped. I assume at the moment that something went wrong and it is basically unsolvable. The description "Warm colors only" seems to imply one thing, but the actual requirement is that you have to produce a certain sequence that is 'totally random' and changes from each trial to the next. Here (My version of level "Warm") you can see that the same input color (green) has a different output triplet each time it occurs. Please check that level!
2) In the manual level selection some levels have some number attached to them (see here), what does this signify?
3) It would be nice if the process stopped when an error happens, so that one can see where it went wrong.
4) A 'single step' speed that waits indefinitely and advances the machine one step when a certain button is pressed would also be 'nice to have'.