Duolingo doesn't get feedback at all
There's a lot of Problems. I've sent problems often by email But it just re-sends me automatic replies. When open duolingo application , Daily goal tab makes it delayed for a while. And there's no sound settings. When i don't use ear phones, i can't solve the listening questions. and duolingo website on mobile doesn't show and work itself completely. Even when setting not to speak with microphone, but it doesn't read questions. And there's also a problem which doesn't show pictures of question. Even though It's free but isn't it going too far..? Please check your problems. I hope it will be fixed as soon as possible.
You could try reaching them by Twitter (@duolingo). When I haven't had a response to my support ticket and it's been an urgent problem, I've tweeted them asking to look at my support ticket (included the number) and then they've dealt with it within 48-72 hours :)
I get frustrated by the number of times I've reported an error and it just NEVER gets fixed. In the French course many English translations are suited to USA English, which is frustrating for UK English speakers as we find our perfectly good UK English phrases rejected. I agree you have to keep in mind this is a free service (amazing!), but sometimes these errors spoil the whole experience - they are too annoying! I don't think Duolingo ever pays attention to error reports, as there are some I and others I've reported on mulitiple times. Grrrrrr