Hey your plants are spectacular and I am am envious. You seem to be a window grower like me so I’m offering this with regard to the roths: it looks from these photos like they need more light. If you know this already, just brush me off but from others who grow roths in windows and struggle, I think the leaves need to be what to my eye is an UNhealthy-looking chartreuse-yellowy-green. Yours look to be about halfway up 2/3 of what I think would kick them over. My main Roth sits with its leaf tips millimeters from the window glass in a due-South window (with some “shading,” but not much, from failed double panes). Also wondering if you supplement with Cal-Mag or some form of calcium? I used to use Cal-Mag exclusively but now with the plants I know like extra calcium I dress with powdered oyster shell about once a month. It mostly washes through but over time I can feel the plants getting something out of it. I still use Cal-Mag during active vegetative growth and cut it as soon as I notice a bud. Again, your plants are spectacular and it always makes me happy to see window-grown plants.
No, rothschildianum leaves need to be green to quite dark green. See the photos of TON rothschildianum as an example, or mines, or the ones I posted from Philippe recently..
They get a lot of light and a lot of food. A roth with yellowish leaves has all the time deficiencies, and after blooming, it will have a very severe setback... Yellow green would be bad news for them. They happen frequently with all nitrate fertilizers, in which case they have not enough nitrogen, an excess of calcium, and a potassium deficiency in the tissues. A 30-10-10 with urea certainly does the job very well...