Actually it cannot be nitrogen deficiency because the older leaves would yellow first. Since the newest leaves are yellowing and the older leaves ar darker, and the fact that you have used an organic soil with compost, it is more likely to be a pH problem and a sulfur deficiency that is causing the yellowing.
https://www.rsc.org/learn-chemistry/cont ... ciency.pdf
Coffee grounds, pee, worm castings and compost does not provide a sufficient quantity of nutrients and may not be complete. compost has an npk of 1:0.5:.05, pee, worm castings and coffee ground provide nitrogen but with the exception of the worm castings it is not in a form that the plant can use until soil microbes convert it into a form more readily used by the plant. Organics in pots are hard to balance because you just do not get a thriving soil web in a pot. The bigger, hungrier plants have the hardest time. It is why when you go to the garden center the organically grown plants are smaller but cost so much more. They have to be fed fish emulsion and compost tea weekly. I don't know how they mix the soil. I tried to do organic in a pot. Compost and manure killed the plants in a pot, too much salts accumulate, the pH was too alkaline and for me it just held too much water.
The following is an exerpt from this site.
https://www.motherearthnews.com/organic- ... cleContent
"In his book The Vegetable Gardener’s Container Bible, Edward Smith recommends the following organic fertilizer mix:
1/3 cup blood meal (for nitrogen)
1/3 cup colloidal phosphate (for phosphorus)
1/3 cup greensand (for potassium and trace elements)
Even if you use the greatest potting soil in the world, amended with excellent fertilizer, after a month or so you should start feeding your plants with liquid fertilizers. Fish emulsion/kelp mixtures are popular among organic gardeners, or you can make your own liquid fertilizers (see Free, Homemade Liquid Fertilizers). Whenever a container-grown vegetable looks unhappy, drenching it with a diluted liquid fertilizer is the first remedy to try."
The other think that can cause yellowing is environmental stress. You said you have been watering and there doesn't look to be a lot of pests however, dusty conditions can bring mites which are hard to see. Hosing off the undersides of the foliage every time you water will help to keep the dust off and knock down any mites that may be in the dust.
These plants are on a roof in the middle of El Nino and P.I. is humid and stifling hot in summer with temps soaring above the century mark often. The pots may be getting too hot and overheating the roots. Larger pots help and what I like to do is double pot and group the plants together so they shade each other. It keeps the pots in the center better insulated. For the outer pots I double pot and if I can get styrofoam sheets. I like to place styrofoam between the inner and outer pot to add more insulation. If the roof is too hot to walk on in the middle of the day. try putting down a reflective sheet to reduce reflective heat from the roof and put the pots on feet to get air under the pots and put some distance between the pot and the hot surface. A rack , pot feet, plant stand, bamboo lashed together to make a bamboo mat should work. Overheating and stress could also be causing the blossoms to drop.
