My stocking levels in both tanks are well below 100 percent, so maybe this applies here. I'm assuming it has to do with lack of nutrients?
No this is not the case here. The levels of nutrients in the two products I recommended are adequate for any fish tank that is not a high-tech plant tank. It is true that the "hard" minerals (calcium and magnesium) are in minimal levels, because most people have these in their source water. The name "Supplement" should not be lost, these products are supplements not replacements. And if they work with my zero GH water, they will work with your 11 dGH water even better (one would expect).
Back to what I have mentioned in this thread...I do not really see any issues with the plants, beyond normal things like different leaf sizes for the swords now being grown submersed. I have had sword plants that were adventitious plants from the same parent plant, when these (adventitious plants) were planted in different tanks, grow differently. This occurs in nature too. Yet I have the same basic light over the tanks, and all receive the same fertilizers, and fish loads are comparable.