UPDATE:
The colony seems to have adapted well to the modifications I made. I don't know which change made the most difference, but I suspect it was adding the screened bottom board. For the first couple evenings after installing the SBB and vent box, the bees continued to hang out on the landing board and up the front of the hive. We had a cold spell then, with a string of nights going down into the 50s. During these nights they stayed inside, and since then, they've tended to stay inside. On the other hand, they've been very active during the days when the temperature has risen into the 80s and 90s. As for the vent box, I left the hole in the inner cover unscreened. The colony has not moved into the extra space there; ocassionally when I peeked into the box, there is a little corpse of a worker who went there to die.
I was also concerned about whether the colony would make the move through the queen excluder and begin drawing comb in the honey super I installed. At first they went down through but didn't come back up, and I thought I'd try putting it on sideways in order to make it easy for them. But they eventually moved up there and started drawing the comb out on at least four frames, when I last checked a little over a week ago. They are drawing it a little slower now than in the past, when I was feeding them syrup. My experience is that they'll take it as long as you give it to them, and because I want them to make honey instead of distilled sugar water, I stopped. But we still have a few months, I hope, for them to draw out some frames of comb and fill them with honey.