Planting Cacao trees in a rolling terrain is a good idea. To prevent your investment from doing Adele’s “rolling in the deep“; here is a suggestion for that undulating hilly / slope area.
Do a terrace construction and/or planting-hole platform prior to your Cacao Planting. This way you could avoid run-off fertilizer, growing trees that fall to its side or cacao pods rolling downhill during harvest. Do that or you could have had it all.