I just read the post. In the first images you showed back in November of blotchy leaves on some of your bamboo. My thought was spider mite or false spider mite. They are too small for me to see, but I recognize the damage. Your rose didn't bring the spider mite in, you already had them. They went nuts on the rose.
For what it is worth, you can to some extent make up for low light intensities with longer day length. I run my light garden with 18 hours of light. All year round, no adjustment for season. Have had excellent results, been doing this for over 20 years.
A fan in your growing area will help with keeping mites and pests down, improve health of plants generally. Still air promotes bacterial and fungal problems. A cheap, box store 7 inch or 9 inch fan left on 24 hours a day, enough of a breeze to keep the leaves moving slightly, will work wonders. They will be fine even if some leaves are "flapping in the wind", though adding a fan may require you to water a little more frequently. Since you are back home, it won't be a problem. I raise orchids under lights, and Chimonobambusa marmorea. The C. marmorea is in its first winter under lights and seems to be doing fine.
Gnat eating carnivorous plants - Pinguicula - the Butterworts. Pretty flowers too. Widely available, google them.
Plieoblastus viridistriata is remarkably winter hardy. I am in zone 5b, Planted in the ground, no winter protection at all, my planting as survived almost 30 years. It frequently kills to the ground, but always comes up in spring, with more culms, and fresh and lovely. Leaves on P. viridistriata that are over one season old tend to look ratty, so in years when the winters are mild enough that the leaves survive, I end up mowing the entire bed with the lawn mower, in late winter before new culms come up. The fresh new growth is incredibly lovely. It is a great ground cover bamboo. I'm tempted to allow it to take over my entire lawn. If you plant it out in spring, it will have plenty of time to settle in for next winter. Plant it where you can enjoy it in spring.
You have a nice little light garden. I went crazy and let mine get out of control. You can tell I am currently single, no spouse would let me get away with this. I have roughly 1000+ orchids in this 2008 photo. Fans are off camera on the right, and behind a ballast hanging off the ceiling on the upper left. Air movement keeps thin grassy leaved plants moving slightly anywhere in the collection. If I had to start over - I would have installed a vapor barrier to prevent humidity from migrating out to the rest of the house. With this many plants in one spot, no humidifier is needed, plants create their own "weather".
