My Chocolate Tree is Unhappy

I keep chocolate trees. They're not too difficult to grow (if you set up an incubator), but keeping the things alive as houseplants without a controlled environment can be tricky. They generally do okay until you have One Bad Day with light levels that are too bright, or too dim, or the humidity's too low, or the temperature is too hot or too cold, and the things panic and drop all their leaves and turn into ugly bare sticks. And when that happens, it seems to take about eight months to coax the things into producing more proper leaves, and get back into the swing of things. Maybe it's a way of outliving predators - if any beasties have eaten the last set of leaves, the tree waits until they and their offspring have all starved to death before growing any more. Dunno.

I had two gorgeous bushy indoor trees last year, sitting by the back window, and moved them to the front of the house where the light levels were slightly lower. One day later, all the leaves had gone sickly. A day or so later they all fell off. A couple of earlier trees got trashed by a few hours of unusually harsh UV light on one clear winter's morning.

After a number of house-moves, I'm now down to just one small tree, which is only about a year old. It had a nice cluster of healthy dark-green leaves. But after just one hour's car journey (on a fairly hot day), the thing had virtually turned albino. The leaves went almost white, apart from the veins, and it's been struggling ever since. Once a leaf loses its "green", it's one short step away from dying completely, and going brown and falling off, and when all the leaves fall off, you're in trouble.

So what I have to do now is coddle the thing so that the existing leaves hopefully last until the plant has decided to try cautiously growing some new ones.
Maybe I should switch to growing something less challenging. If I used a set of mirrors to catch and redirect daylight around the room, indoor climbing roses would be nice ...