The soil mix is way too hot for seedlings (even freshly rooted clones don't need much until they get established). The soil as it was out of the bag had enough nutrients to carry you through for a couple weeks before feeding them.
At this point I wouldn't do much but water them, keep an eye on them and let them grow. They may eventually adjust to the soil or they'll shrivel up and die. Either way making drastic changes will only stress them out and push them closer to death.
No matter what you do you'll want to learn from this and apply that moving forward. You can't grow plants in a textbook, so while book knowledge is great, experience is where the rubber meets the road.
Just know that early on the plants are delicate and don't need much to survive and thrive. When you feel they need feeding take it easy by going 1/4 strength and working your way up from there. A couple feedings at 1/4 strength, then 1/2 strength, etc. You can grow most plants very well at 1/2 strength. Water, water, water, feed is a common pattern many growers tend to follow. If needed you can use toothpicks in the soil to let you know how many times you've watered them with just water. After your 3rd toothpick, fertilize them, remove the toothpicks and start over.
I wouldn't worry too much about pH right now. Just keep it simple. Many grows are screwed up by the grower adding chemicals to their soil because they "thought" it was off. The soil does a great job of buffering your pH and unless your tap water is way off in ph and dissolved metals (ppm) it should be fine.
You may want to add some
calmag to your tap water if you start seeing a calcium or magnesium deficiency, a good ppm meter will help you decide if its needed. Its important to know your water as well as your soil, so get the right tools and find out where they are so you can proceed and make the right decisions to help their overall health.
Remember growing is about keeping them happy, not force feeding them things to get them to bend to your will. Allow it to grow and be a plant and it will reward you with smokable fruit. Mess with them and they'll become unhappy and you'll end up with frustration and more questions than you'll have for answers.
You goal is just to keep them happy. Only make incremental changes when you see issues pop up and when you do, don't do anything drastic. You can't fix most problems in a day. Check the new growth for signs, not the old damaged growth. Damaged leaves in most cases will never recover. So keep an eye on them but don't take their word for it. Check the new growth, it will tell you how the plant is growing and wether its happy or not.