Very carefully, dig the roots up and transplant to a new pot with fresh soil.
Wash the roots very very gently with a 1% soution of hydrogen peroxide then clean water and then replant.
You had too much going on in the soil with the rockwool.
Water once lightly, just to dampen the soil and leave it sit for a couple of days and see what it does.
If you can extremely gently remove the rockwool, it should help. In my thinking, rockwool is like wearing a facemask. It just holds the germs in front of your face so you can breathe them in more often. Who knows what was in the shop where you got it.
Root structure and your absolutely right. There is a difference and it takes time to transition. Light will always make any stress worse. Clones need enough light not to flower and that's as simple as leave the room light on.
My younger plants will do this sometimes but not as drastically as your picture. That did look underwatered. Sometimes after I water my young plants the leaves will droop some but that's just from them taking in water and will usually perk right back in a hour or so after.
I Try to collect some rain water when I can. Even off asphalt roof it's really clean. Has perfect ph and only 4PPM on my machine. I will bring it in immediately after or as quick as I can and boil it and put in jug. I tried keeping outside and mosquito larvae ended up growing in it even with bleach treatment and cover.