If this is your 75 gallon from your sig, unless the wisteria is being blocked by other plants/decorations light level shouldn't be an issue.
Do you have a picture of your tank? Wisteria is a very fast growing plant that can deplete nutrients quickly in a tank. I would recommend being on the lighter planted side of things if possible.
I also think nitrAte is not a possibility due to your stocking level and species. I assume you got the dry ferts from Greg Watson? Pick up a pound of mono-potassium phosphate and dose that on days you are not dosing CSM+B (they are incompatible). That would rule out phosphate as a possible issue.
I would also switch to dosing the Excel every day, but the amount I'm not sure about (maybe just 1 capful each day, but that seems like so little). You have a big tank to be adding a liquid carbon source, but pressurized is obviously a significant expense and DIY isn't really practical.
At this time if its not a phosphate issue (which is somewhat unlikely due to feeding your fish which normally has a good bit of phosphates in it), I would lean towards a carbon/CO2 deficiency. If you have a GH/KH test kit that could help us understand your other macro's (Mg/Ca).
HTH