"Ydy hi'n ddrama Gymraeg?"
Translation:Is it a Welsh-language play?
Sometimes, "Welsh play" is dismissed in favour of "Welsh language play" but nowhere is "iaith" mentioned
See my comment above. In this case the word used clearly suggests Welsh language is meant although I agree that Welsh play seems to be a perfectly good translation. I suppose the course creators wish to demonstrate this subtlety of the language.
Is saying "Welsh language" necessary, or could you just say "Welsh"?
I think I raised a "my answer should be accepted" on this for the same reason. However there is some subtle meaning here: Cymraeg means Welsh but more with the sense of Welsh language. The word Cymreig means Welsh with more of the sense of being from Wales. Thus there is a subtle meaning of "Welsh language" being conveyed here.