I don't have any experiences with cacao. But I did have similar issues with my mandarin that was in a pot so many years and got root bounded sinceI never repotted it. It was on the verge of dying with leave mostly yellow. Then I decided to repot it and at the same time cut the bounded roots off ,and amazingly, it came back to live really fast and it has lushes of green leaves and larger plants as well. So, I'm not sure if it was the soil or cutting of the bounded roots off that did the work. That was about 1.5yrs ago. I will need to do the same thing again next year. This time, I will pot it into a 10gal nursery pots so that I can later on cut the bottom off and just let it grow into the soils.