No, I understand which form of each verb I used. It seems irishdictionary.ie switched the entries for the verbal noun and adjective, so that's not my fault.
I'm not sure if you mean it doesn't sound right In Irish or English, but "music that is sung in other languages" sounds perfectly fine in English.
Furthermore, the Learning Irish book says "cas" means either "turn", "sing, or "play" (Kinda weird, since those words are toatlly unrelated :/ ), so I'm sorry I listened to what it said.
Níl aithne dom amhráin ar bith as Gaeilge.
Is fuath leis an duine atá i mo dhiaidh an teas.