I wholeheartedly agree. While I admire OP in his charitable endeavors. I can't help but think that this puts the incentives on studying things that offer little to no market value. Market value of a degree tends to be a huge predictor of how needed that skill is in the market. I don't know if what Tanzania needs right now is language PhD's instead of Architects, Engineers, Doctors, etc...
One thing they probably don’t need are bad unhappy professionals uninterested in their field. The people from the village know better than us random internet commenters what their heart is in, and they have just as much right as us to pursue their dreams and interests.
The focus on “the market” is a disease which narrows our thinking. For all we know, her language studies might allow her to communicate with many more people and cultures from the outside and bring much more prosperity to the village than an architect.
IMO this kind of hyperoptimization will cause more trouble than good. It's cheap and productive just to get humans to advance through any sort of education. This person will almost certainly contribute more than she would have with a 5th grade education.
Let people self-direct, even if not everyone follows an optimal route. It's a numbers game.