The problem with calling some languages "local"

Only in Africa, it seems, can a language spoken by millions be called a "local language." The term is used widely, not just in Africa, and although I've also used it, I'm increasingly finding it problematic as employed in African contexts for two main main reasons:

1. It is inexact, often serving as a catch-all term for languages other than the main Europhone official languages, from those like Akposso that are truly localized in use, to languages like Hausa spoken across many borders by many people of many backgrounds as a first or second language. 
2. It is misleading. As a term, "local language" implies a low rank of importance relative to "official language" or "language of wider communication," when for some languages and/or in some contexts such a hierarchy of importance would be inappropriate. In Senegal and Mali, for instance, Wolof and Bambara, respectively, are spoken more widely than French, but are sometimes referred to as "local languages." Such indiscriminate use of the term arguably pigeonholes languages and disincentivizes thinking about their use in communication, education, extension, etc.

At this point, I'd like to suggest that more thought be given to using the term "local language" when speaking and writing about African languages. It probably should be used much more sparingly than it is now. Sometimes a language really is local, but other times, what we may call "local language" in Africa is actually more widely spoken than some European languages that we probably never would call "local."

It may be that a key piece in more deliberate use/non-use of "local language" in Africa is informing development, health, diplomatic, and other specialists about the sociolinguistics, culture, and policies regarding African languages in areas they work. Should a basic course about African languages and multilingualism in development and contemporary society (this is different than studying a language or intro to African cultures) be part of the education of non-Africans planning to work in Africa?