Mixing Micro and Macro Dosing Solutions?

Plants cannot be stunted due to excess nutrients unless you get out to about 10X the ranges produced by EI.

So no.
You can find stunting data for soil solutions used for many agricultural crops and exposure, they are very high. Hydroponic solutions are also extremely concentrated, yet most of the aquatic plants sold today are raised in.....hydroponic solutions.
Bathing plant leaves in a solution, no less than 10-20X less, is not problematic.

Some folks who have been critical of EI, or higher levels enjoy spreading fear rather than using common sense it seems.

The irony is the very plants they buy come from super strong nutrient solutions already. You can also look up "modified Hoagland's solution", it's a standard for non limiting nutrient levels in research.

This is easy to show to be false through a simple test in aquariums. You add it and you do not get stunting. But you need to be able to grow plants well to begin with and produce a control tank that has no issues.

So if you have problems growing plants, it could be many things, generally CO2 or poor maintenance, many look to blame all osrts of things, often nutrients, and claiming excess nutrients causing problems is as old as the Hills.

You can kill/burn/stress plants with NaCL, Copper, Excel over dosing, really high levels of NH4, maybe Cl- at very high levels, H2O2, bleach etc.

You have to go above 80ppm NO3 before you see any decline in growth rates and stunting likely does not occur unless you go way out there. I never saw any at 160ppm +.

Generally, folks make KNO3+ KH2PO4 in one solution, the traces in the other.
I like Tropica master grow of all the traces I've used.
Never liked CMS. It's cheap though and it does work.

Some add MgSO4 to their KNO3/KH2PO4 solution also. Some make a GH booster solution etc as well.

So traces, macro NPK, and GH Ca/Mg.
Note, K2SO4, tends to be pretty hard to dissolve. Same with CaSO4.

Regards,
Tom Barr