David, I'm looking at your first picture on this thread and thinking "why aren't there any plants on that top shelf??"
It's got to stay at lot warmer up there during the day, and warm air holds more moisture, too. Might be worth a try to place some of your struggling plants up there for a week or so to see if they rally. Put the books down on the floor by the window!
I agree with Tarev, the plumeria are dormant now, just keep them cool and water very little if any until the weather warms up. The cutting may still survive, if the stem still feels firm. If it's soft and squishy, pitch it.
