I am not one of the smartest plant guys on the net by far, but I do have a lot opinions.
One opinion is that one shouldn't stress his fish by injecting too much CO2. I don't know at what level fish start to be stressed. It probably depends on a number of other environmental factors. I read somewhere that plants can't make use of more than 30 or 40 PPM of CO2. So consider cutting back on your CO2.
I assume that you mean that your pH and KH test kits are "crappy" and hence the calculated 60 PPM level is questionable. It might be, but since the fish are showing signs of stress it might not be, too. Until recently there was no reasonable alternative to those "crappy" test kits to estimate CO2 levels and yet people were able to create wondeful plantscapes.
Since you are using EI I won't suggest testing your water for nutrients, but you might consider increasing the dosing. But I really don't know much about that.
Good luck.
Bill