How long does it take for your language to get approved?
I suggested a language and Duolingo hasn't responded and I don't know if they rejected it or they just have not seen it.
From what I've seen on the forums, Duolingo doesn't respond to applications through the Incubator unless they decide to launch a course and use you as one of the contributors. No-one knows how they decide which languages to add, and apparently they're not telling. Even if they do decide to use you, it could be a very long time - months or years.
They do (or at least used to) send an autoreply, just acknowledging your application. It seems some people have thought that was an actual reply from a real person.
I doubt they even lool at the applications for a particular language pair unless they are already interested in making that course.
Not sure how long it takes for them to answer you, but generally Duolingo has its own mind on what languages should and shouldn't be added. You can always "suggest" a language, but it's really just a suggestion for them.