I had those spots in the old leaves many times and they also may be a sign of too much watering, but i would not worry too much about anything, if the overall plant looks ok and it produces flowers\pods normally.
I usually get these spots at the end of the season.. so I think it's a nutrient issue, but we'll see. I don't think it will hurt to give the plants some CalMag, quite the opposite.
Nice O/W soon be pushing out flowers ... all the best for your coco grown and a fruitful season
I've already had a flower or two but didn't bother with pollination. Want it to grow slightly more first.
Everything's looking great, best of luck this season