The art of spotting is to know when to leave well enough alone. I use 99¢ 3.5 diopter glasses to spot under strong light, then change to normal reading glass strength (1.5 for me) to evaluate the print. If the spot is no longer noticeable at this point, it will be all but invisible at normal viewing distances, and I am done.
I've tried "spotting pens" on recalcitrant spots many times. In every case I've had to return to brush and spot tone inks.