Huh? Lots of issues affect leaflet edges.
Yes, but nitrogen deficiency was what I mentioned. So, I don't believe it's nitrogen toxicity.
I think many growers would say
FFOF is hot. That's somewhat relative, of course, but it's surely hotter than FFHF, to which it is often compared. It's generally agreed that plants started in
FFOF don't need additional nutrients while they're young.
It could be a watering problem. It doesn't look like it to me if it's nutrient lockout, though. Rather than watering on a schedule, a better method is to lift the pots and become skilled at knowing when the pot is light enough to need water. I call it the dry-and-drench method. Many growers recommend it.
They do indeed measure light, but that isn't always helpful. You're right if you're saying that the various growth factors all need to be in optimal ranges for optimal results. Reducing light intensity, however, would be helpful if it lets the plant recover. Many growers, me included, prefer to let the plant be the light meter. Because plants vary so much in their needs, conforming to a textbook-type standard can fail. There's nothing better than learning to read the plants. It takes time to learn, though.
It's always up to the grower to decide. We give them our opinions. They might believe us. They might not.