The pH is not the problem. And on the pH, do not mess with trying to adjust it. The pH is related to the GH and KH, especially the latter which serves to "buffer" pH and prevent fluctuations. Your KH at 300 [I assume the unit of measurement is ppm or mg/l with a number this high] is high so the p|H is not going to budge. This is more of an issue for fish than plants, but I'll leave that.
The GH at 75 [again assuming ppm or mg/l] is fine, not a problem.
Eco-complete in my opinion is useless, but it won't hurt the plants. However, it is sharp in texture and substrate fish may have issues. I'll leave that.
Fertilizers. Root tabs are good for swords, but I would recommend the Seachem Flourish Tabs rather than the API. I cannot find out the ingredients in the API, other than they say "including iron, potassium and carbon." I'm a bit skeptical of how carbon could be in tabs...but regardless, there is no mention of the 14 other nutrients plants need. I would change to the Seachem Flourish Tabs. I do know that I have read negative comments on the API, including the mess they can make if disturbed. I've been using Flourish Tabs for years with no issues, and they do improve swords.
Same holds for the liquid "Leaf Zone." It has iron and potassium mentioned, but nothing else. Here I would get Seachem's Flourish Comprehensive Supplement for the Planted Aquarium. It is complete, and the nutrients are in proportion to what plants require. I use this myself and have for years. Make sure it is exactly the Flourish Comprehensive Supplement..., they make several products under the "Flourish" name. You do not need any of the others.
Light. Aqueon make three types of fluorescent tubes. I've had them, as a couple of my tanks came with Aqueon hoods with the tubes. The full spectrum is not bad, but not great either; the other two are useless. See if you can find a Hagen Life-Glo T8 tube in the same length, 20 inches. I'm assuming the fixture takes T8, most of the basic do, this should be printed at one end of the tube; T8 tubes will fit provided the length is the same, and the Life-Glo is the single best fluorescent tube for planted tanks, bar none. It is more intense, and has exactly the right spectrum. I use this on all my single-tube tanks.
Temperature. Why is the tank at 80F? That is quite warm, and this will affect some plants, though that is not the issue here.
Medications. Some of these can be devastating to plants, so this may not have helped.
Nitrate at 20 ppm is as high as you ever want it for fish, and it would help to have it lower. Is this the nitrate in the source (tap) water? Or what occurs within the aquarium? Test the tap water alone for nitrate and see what it shows.
The above should solve the plant issues.