Duolingo, thank you!!! Living in Spain, you have helped me a lot! I find it now easy to read the papers and write (short) messages to friends.
Problems arise however when the language becomes more informal, watching the telly (especially comedy) or listening to conversations between Spanish friends. I wish there was some way that Duolingo could help me with that! I feel like am still missing some language essence in order to communicate fast enough and keep up.
Also, sometimes my friends tell me I sound South American with some of the phrases I use. I am happy with the street creds, but It would be nice to have more control over these differences.
At the moment, you are right, Duolingo does not teach a lot of informal speech and conversation skills. The later might come at some point, the earlier is not feasible, I guess, because of so many regional differences (not only between South America and Spain, but I assume also within South America and Spain themselves).
I think the course started out being more biased to South American spanish, so yes, it may teach you a lot of those thing. However, Spanish Spanish should always be accepted (if it is not, hit the report button).
I think it is unlikely that separate South American and "Spanish Spanish" trees will be introduced soon (if at all) - probably the other languages will be taken care of first. The differences between SA and Spain are not big enough to make separate trees really necessary (from what I hear).
I think you are doing the right thing watching television shows and engaging in conversations as often as you can - this is how you REALLY learn the language. :-)
Berend, how frequently do people in Spain really use Vosotros/Vosotras? I didn't encounter these at all in the Duolingo tree which makes me think it skews Latin American, though I understand that Argentenia and other regions still use variations on Vos. I'm OK with a hybrid environment but it would be nice to have a module dedicated to learning these differences.