hey GranDadPurpler, its def leaf miner, will serious damage the foliage which its overall important to make this plant healthier that will get more yield. I just said in the first post. If you can go to the hydro store or order online to buy the Dyna-Gro Pro-Tekt , its Silica that will help your plant more strudy and strong that can resistant to the pests and fungus and plus bonus for more resinous, I love this Pro-Tekt no question. Dyna-Gro Neem oil is also good one...i mix em both and spray plants from bottom to upside leaves. it will stop pest from eat your leaves.
About the gnats...i really hate it when i have organic grow...either i got a bad bag of diesase borne. Make sure buy the good quality soil or if you make organic soil with poop stuff then let it cook over month your will be good to plant in that soil. As now for your problem, try to cover with all purpose rock that sell from homedepot and cover on the top...so gnat flying cant go up then you water in it. It will drown em down !! I wish ya a good luck, buddy