I'm going to guess you're problem is pretty heavily skewed towards the lighting. I don't think you're giving them enough. In my experience, corals brown out and lose colour when they don't get enough light (just turn a coral that's been in your tank for a while upside down and look at the normally shaded tissues under your tank lights!), but they will still extend their polyps. When they get too much light they will bleach out. I know it's only a 20 gallon, but 38% is really low for a radion over SPS if it's mounted the standard 8 inches above the water surface.
I know you dropped the lighting intensity because you saw the polyps react to the increase in light. Polyps are the most sensitive part of the coral, so when you increase lighting intensity it's going to take them a while to adapt and start coming back out again (maybe days to weeks). So long as the coral isn't bleaching or being damaged in any way that's fine. It may also be true that the intensity of the light that is required to get them to colour up properly may be high enough that they never really extend their polyps that much during the day. There are dozens of corals that only really send their polyps out for the 'full show' at night, so if I were you, I wouldn't worry about the moment to moment reaction of the polyps, but instead slowly increase the light by about 5% a week (or every 10 days even), so long as the corals show no sign of bleaching.
FWIW, I have 8 radions over SPS running at a peak intensity of 78% at 12K (all channels at 100%) for 6 hours every day. All of my corals go through a serious adjustment once they go in to my tank, but they all adjust. If I was being fair, I'd say the "full" adjustment for a piece of SPS under my radions is about 2 months, and in that time they usually change colour significantly from when I bought them - thankfully usually for the better. They also usually go through a week or more where they barely show their polyps at all, but they all get over it.
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