Far be it from me to offer anything definitive--you are certainly far more experienced than I am--but I will say this. You can grow a plant in less than optimal light. You can even bloom them. The plants will certainly look healthy if you're meeting their other requirements (temperature, water, humidity, nutrients). They probably won't, however, grow as quickly or bloom as frequently.
I grow under fluorescent lights and (mostly) grow plants that are tolerant of low light. (In other words, Phals!) Yet, I've bloomed Oncidium species and intergenerics under these lights, as well as a couple of Dendrobiums. I think they would bloom much *better* if they had more bright light, but they do bloom.
And, yes, some of them have fairly dark green leaves. Surprisingly, though, some of them have quite pale leaves (such as my Onc. ornithorhynchum) and I can't help but wonder if these ones are missing some micronutrient(s).
BTW, many of my Phals have red-tinged leaves so I am confident they're getting enough light.