I may be wrong, but I don't think drawing language lines in this conference is of any importance. Whatever the different countries that come, the default language to be used will be English. The conference is for Africans, not anglophone or 'portophone' or whatever. Of course, attendees are free to speak language they are comfortable in when they attend.
Sure, English as default makes complete sense but there should be tracks (sessions) in languages other than English. Not everyone in Africa speaks English, not even everyone in Africa involved in Wikipedia speaks English ;) and this should be acknowledged. If all sessions are in English there's no point for people who only speak French, Arabic, Portuguese and a bunch of other African languages but no English to go to that conference.
To make it a conference for all Africans a lot of effort should be put into making WikiIndaba accessible to Africans who don't speak English. As far as I know most Africans don't speak English: https://en.wikipedia.org/wiki/List_of_countries_by_English-speaking_populati...
I also must say that, I've hardly known Douala if not for my WiR in za. However, I cannot say for sure that, because myself or one or two of people I know doesn't know Douala, for that reasons, Douala isn't reaching out to many or Douala is making poor country-based representations.
Douala was just a session with 15 people (including me and other trainer) as part of the Afripedia training sessions.