The problem with exposing other color films selectively is that the sensitizing dyes are designed to wash out easily whereas in Kodachrome the sensitizing dyes must survive at least 2 development steps. Therefore, selective light re-exposure of Ektachrome or Fujichrome will probably not work. After the first developer, the films are no longer Green or Red sensitive, just Blue and UV.
As for the Rockland couplers, they are probably quite good but not up to the quality of the real things. IDK for sure. I have seen some of the colors, and they appear to be mixtures or rather poor as dyes. But, not having the real data, I cannot say. I imagine a fairly good Kodachrome type could be made, but as for the Ektachrome, probably not.
BTW, the Ektachrome reddish greens and etc, the false colors, are designed the way they are to reveal camoflaged items. It was developed to detect camoflage in WWII and then was extended to be used to detect diseased plants in forests and fields.
PE