Some of the elemental numbers are off. Example: Ammonium Calcium Nitrate is 14.5% Nitrate and 1% Ammoniacal. Magnesium Nitrate's Magnesium content is 9.6% vs the 25.6% you have in the inputs. That's why you're off a bit in those areas.
So if I were making a set of products targeting 15% Ammoniacal to total Nitrogen, and extra Calcium and Magnesium to make up for RO, it would probably look something like the chart below. FN Silica and FN Micros are stock products that I do not change. I just play with FN A and FN B to get to my targets. In this case I dropped the Ammonium Sulfate from FN B because I'm not needing the extra Ammoniacal Nitrogen source, and switched to Magnesium Sulfate instead. As an added bonus, Magnesium Sulfate (Epsom Salts) are a lot cheaper than Ammonium Sulfate. Lastly I tweaked the weights to get to the ppm goals.