First grow

480 PPFD and 65% RH sound perfectly reasonable. I’d look at watering first, every 3 days on a fixed schedule can easily keep the root zone too wet. Go by pot weight instead and let it dry back properly between waterings. Also check temps/VPD and make sure the fan isn’t blasting the leaves directly. Dry/papery leaves can come from environmental stress even when the light itself isn’t too strong.

Would be helpful to know what the ph was before you started the flush. My opinion they are not looking particularly bad right now. Maybe they looked worse and they got better. castings are like Neosporin for plants. lol if you truly think you soil s wrecked If these are photoperiods. and you have a little extra cash to spare. I would just make up some new soil or buy some. and transplant after insuring the ph is where you want it. Its really a shot in the dark trying to correct this soi with plants living in it. Some plants will tolerate it others wont. its like trying to renovate a home while your living in it. if you feel like it is getting weak, don't hit it too hard with anything at once. start with something gentle like kelp and worm castings if organic or low dose if with bottles.

Here I would totally disagree with the previous answer. I have a huge respect for ultraviolet ( think its his nickname ), but he speaks about Coco and you are in soil mix. I told you previously that it's stupid to grow in such mixes because exactly of one of such situations as you are in now. There is few golden rules whrn growing in soil. Less is more !!! You never flush in soil. In soil, you control what you put in not what you are getting out. I don't know about your coco but sometimes it's sold not pre-buffed, maybe that's the answer to your issue. Plus I would really want to know how you collect it . Do you really put clean plate under the pots and collect not first not last but middle part of runoff and that's the thing you measure, is it really so ? Have you checked your measuring equipment. I had always triple comparison system where my meter was put against strips and against something stable, which I know is always keeping approximately the same pH. Meters tend to break or go bad that's most common mistake in soil growing. Check and keep safe your equipment constantly ! Ph is essential. With those flushes you just ruin all micro fauna, leave pots moist for long time, what causes more salts to build up, rot and ph fluctuation. Do you really have those issues ??? you haven't showed us your previous leaf problems I see only nice growth , so maybe you are panicking again ? In soil and organic grow ( even worm castings is kind of slow release nute version, which is not balanced diet, but more as desert on your table after healthy meal) you preplan your feeding schedule, most of things you do now, will have effect after few weeks. I would return to good wer/dry regime. Would control what i put in and only if i would have troubles, i would be checking runnoffs and etc. You are growing autos, they hate panic and instability. Stop and rethink what, how and when you do something. 70% of soil in mix is still dominant, you have to obey soil ( not coco ) rules !

For soil grows 1800+ is a bit too much. I personally when do such strong mixes for feed, means i underfed her before and thats my temporary fix/boost. You have nitrogen toxicity, leaves are clawing , easy solution : just back off with feeding, for 2-3 watering cycles , she would be on plain water diet in my garden. After that break return to 1000-1200 ppms, for not running into same problems : feed/water/feed/water is smart feeding schedule . Leaves should be ok after some time.