I'm afraid you have bought into a few really detrimental myths about growing plants and it is the cause of some of your problems. I won't get into diagnosing your plant pictures I find the interpretations highly speculative and I lack the experience of some of the others to do so accurately.
1) The first thing is you cannot possible be sure how much CO2 you are adding to your tank, you can't control how much the rock dissolves(Calcium Carbonate) from CO2(Carbonic Acid). You have to get rid of those rocks or you are just running blind and won't ever have control over that part of your tank. Its possible you have a CO2 deficiency what is your degassed starting pH?
Running with fluctuating kH is difficult even for experienced Aquarists who know how to diagnose plant issues and dose, it definitely doesn't work well with EI.
2) Excess Iron toxicity or Phosphates are extremely rare and you can't have both because Iron Phosphate readily precipitates out of solution. Chances are pretty good you have neither in excess and should not have stopped dosing either. You are limiting N uptake from 1ppm(phosphate) you should be instead dosing a target concentration of 5ppm phosphate for 15 - 30 NO3. EI is about dosing more than your plants need and then doing 50% water changes weekly to reset levels. The excess ferts does not hurt your system and that is the primary ideology of the method and it works especially for heavily planted tanks ( you are not there yet but it still can work for you).
You shouldn't be dosing "Partial EI" everything should be balanced in proportion, CO2, light, Macros, Micros, Calcium, Magneisum. Its not a problem dosing Seachem equilibrium but chances are that won't solve all the issues.
Take a look at what some of the successful aquarists are dosing to give you an idea of what levels are working for them and try to apply that to your tank.
If you want control over your tank I'd ditch the Carbonate containing rocks and remineralize your RO water to kh=2 - 3 and gH=3 - 5 you can read up on those values. Once you do that you can get a better ballpark for pH drop and CO2 levels and will create a more healthy nutrient balance for your system with less unknowns.
The other methodology if you don't want to do that work is what SA is suggesting is to up your Potassium, Calcium and Magensium, which may work, but you might be dealing with issues due to excess Calcium from your rocks, which leads to -Mg or -K type problems. Even so along with Equilibrium I would really up your Phosphates so you aren't dealing with a -NO3 uptake problem.
I also wouldn't stop dosing Micro although they are less important to balancing your system at this point. Target dosing of 0.75ppm Fe is prescribed in EI dosing so I don't know who told you that was a problem.
If you have Macros(NPK) and Micros in non limiting quantities your light and CO2 will be limiting instead of your fertilizer and that is most likely to provide more healthy plants.
Once you make a change look at the health of new growth, you can't fix old leaves in most cases. Once you see good new growth you may be best to top and replant your stems and remove all unhealthy leaves.
Addition: Amanos don't eat healthy leaves.