Well, it being the plants that are seemingly getting the most intense light, it leads me to believe that they need more bloom nutrients, as the leaves that are producing the most energy are the ones yellowing. Do you have a thermometer that you could hang at the canopy level to check the temps? The leaves in that very last pic are really dark green, which can be a sign of nitrogen toxicity, if you are giving them their bloom phase nutrients than there should be no need for the grow nutes...I'd totally cut them out, especially at this stage, N toxicity can really hurt yields. With those leaves not getting dry and crunchy, I'm really leaning towards not having too much Nitrogen and not enough PK. I could be totally wrong here, but that's just my take. How long have you had them on this dose of nutrients?...Has it been a while since you've increased their bloom nutrients? I'd start there, maybe increase the bloom nutrients by about 15-25% and see if they perk up. The leaves might not recover, however, the new growth will be green and normal again, and that's how you'll know you fixed the problem
We'll figure it out! You're almost to the finish line!