Well, this is interesting. This evening, Damiri took advantage of a not quite fastened door to escape from her cage, and crawled under the bed. After I finished cleaning the cage and Charlotte's litter box, I placed a bowl of food on the floor, and lay down on the bed to wait for Damiri to come out. Charlotte came out to keep an eye on me. While I waited, I kept hearing odd noises under the bed: thumps, an extension cord rattling, something being knocked about. Damiri was playing! And quite happily too.
What I am thinking about doing is letting Damiri run around in the bedroom. I want to block off the underside of the bed so that I can still pick Damiri up and cuddle her, but also let her choose what to do. Jackson Galaxy of My Cat From Hell recommends that cats be given high places to hide instead of holes to crawl in. The only real hole is the underside of the bed, and I can borrow a cat tree from the resident cats so that Damiri can climb on top of the furniture.
Please keep in mind that everything I know dealing about cat behavioral problems, I learned from owning a reverted feral who was probably neurotic, and a TV show. I kind of faking it here.