"Gaelic is so fun!"
Translation:Tha Gàidhlig cho spòrsail!
Sean, for what it's worth, the course is from US English to Gaelic. "So fun" sounds wrong to me as well. "Such fun" or "So much fun" would sound better to my ears. It's a bit tricky for those who speak UK English or Australian English, but you'll get used to it. Of course the Gaelic version is right.