i think what you see now is because of how much water you are spraying on your leaves. the burns appear to be on points of the leaves where the water collects (in the veins and the tips). this could be for one of two reasons either the water drops are acting as magnifying lenses and the lamp is burning them or the plain water has some sort of residual that the leaves find irritating or perhaps the pH of the residual is having a local effect on the leaf tissue. hope this helps you. it looks like you are doing pretty well for not being an expert. good luck you'll be one soon!