I grew up hearing about my mother's Swedish mormor. She spoke English well, but at the end of an evening's visit she would announce, "Jag gå hem nu." When she said that everyone knew it was time to take her home Now. She was a liten kvinna , but she was also "She who must be obeyed." :-)
These types of creative spellings that follow spoken vernacular also exist in Swedish. "Sa du?" = "Vad sade du?" for example. In general, it's just asking way too much to add all of these variations, one by one, into the Duolingo system. Also, most people do seem to prefer learning the normalized/formalized version of languages for writing purposes. Especially in the beginning. And let's be real, Duolingo is an intro course.