My limited experience tells me that the best move right now is just to leave them alone. Foliar once or twice a day depending on your humidity. Can pretty much drench them. Keep environment on point as best you can. Keep reminding yourself to leave them alone. Once roots are established, you'll see them blow up. Right now, growth is gonna be slow. Leaves are still little and small. As more nodes grow, leaves get larger and growth will follow.
Do not let them dry up entirely. If you need 5 litres to achieve slight run off in a 5 gallon pot, I'd say it may be too dry. Especially for seedling stage. Most living soil tutorial will recommend to keep it moist at all times. Non living/organic soil grows will usually recommend till top inch is dry to touch. Not bone dry. But dry to touch.
Most growers, even organic growers don't feed for around first 10-14 days. Some even more. Your Super soil should have more than enough. Most do plain water or some enzyme, microbes, coconut water, aloe vera etc. Maybe a Fish Hydrolysate, EWC, alfalfa Meal etc. booster if N is deficient. Not really anything nutrient rich But rather to enchance soil health that will in turn feed the plant. Even If they top dress or add any amendments, its for them to break down in 1-3 weeks, for future availability.
I briefly read through your updates and while I can't remember all details, it seems you have been very busy with your plants. The early stages, they are quite fragile. Leave them alone for the moment and let them build their base. PH the water you give them and all should be good. Add some myco or any beneficial bacteria you may have into the dollar and/or watering. That should make the roots happy!
Hope this helps but please do note that I'm a newbie myself.
