What this headline completely fails to convey is that the main limiting factor on hippos in Africa is not hunting pressure but is instead habitat loss due to human development and climate change/desertification. Hippos are aggressive and territorial, so large numbers of hippos in areas settled by humans just trying to eke out a living along a river is not a situation that works. Almost all habitat capable of having hippos without conflict with people in sub-Saharan Africa already has hippos. Assuming that we can just take these deadly creatures and put them in Africa somewhere is just another case of assuming Africa is not widely settled with farms and human habitation. It's another legacy of colonialism that even well-meaning conservationists can wind up exercising and it needs to stop.

The only substantial population of hippos limited by hunting pressure is in the DRC where they were eaten during some of their conflicts, but there is little protection for them currently and the region is not exactly stable, so they might just wind up killed even after and expensive relocation.

Even then, though, the Colombian hippos are descended from a small group (less than 5 I think) and have almost no genetic variation, so relocating them to anywhere in Africa will just result in a more inbred hippo population in that spot.

We might be able to hope that eventually their inbreeding will catch up to them and they will die off naturally before expanding to other regions, but it's not clear that that would happen.