The amount of pink cure you used it fine, I use 1 tsp of pink cure and 3 tbsps of kosher salt per 5# of meat.
I normally mix at night and rest in the fridge to stuff and smoke the next morning. Did you mix it well? Cure should make it all darker red once cooked. If you have light spots I would wonder if you didn’t get the cure mixed in well.
I am not familiar with the thermal process Waltons must have. I use a smokehouse and smoke low to dry casings and set in smoke flavor. Then later to hotter. If you got to 160 IT, you are fine with kill bacteria and can eat it. I still question the dark/light you speak of. Pictures would help.