Question: I am a naturalized American citizen of African descent. I speak and write French fluently though I am an anglophone. Would I be allowed on an Air France flight departing from New York to Cameroon, even though I don't have a visa for Cameroon?

I have made negotiations for a visa once I arrive at the airport in Douala.

Answer: 
According to Timatic, the system used by most airlines in determining if you meet the requirements for travel to a specific country, a US citizen CAN travel to Cameroon without a visa in their passport under the following conditions :

> 
> Passengers with a confirmation letter that a visa has been approved
>  can obtain a visa on arrival. The letter has to be issued by the
>  competent authorities of Cameroon.
> 
> 
> 

Presuming the "negotiations" you refer to include a letter that meets these requirements, then yes, you will be allowed to travel.
The actual visa policy of a country is not always exactly the same as what is stated in the relevant airline manuals or on wikipedia. E.g. even though the manual says that you cannot get a visa on arrival, in reality this may be possible.

HOWEVER: people at the checkin counter will only trust their manual. The only exception would be that an airline representative tells them that a visa on arrival is possible. This sometimes happens when flights are flown by national carriers (e.g. Air Cameroon). Such a scenario is rather unlikely if you fly Air France and have connecting flights. It is not a risk I would be willing to take unless I were very certain that this works for my particular connections and my particular airlines.