I understand that '(the) Welsh (language)' translates as y Gymraeg.
But in a previous exercise I had to translate 'Do you want to learn Welsh?', and I wrote:
Dych chi eisiau dysgu'r Gymraeg?
but this was wrong, the right answer being:
Dych chi eisiau dysgu Cymraeg?
According to Shwmae's comment, dysgu'r Gymraeg should have been accepted.
Now I'm a bit puzzled about the use of the article before Cymraeg , or the name of any other language.
Dych chi eisiau dysgu'r Gymraeg? and Dych chi eisiau dysgu Cymraeg? are both right. It's just this Duolingo course hasn't been put together very thoroughly in parts, so right answers are marked as wrong.