Unfortunately, a wee mistake was made in Tree 1 so the answer reads as "Tha i cho fuar ann am Fionnlainn."
The correct translation of this sentence is "Tha i cho fuar anns an Fhionnlainn."
Finland is An Fhionnlainn in Gaelic, and not 'Am Fionnlainn'. Sorry for the confusion, but both will be accepted here, and it will be fixed in Tree 2 :)
Cool. I just read silmeth's explanation - see https://forum.duolingo.com/comment/38646014?comment_id=38647793, and was prepared to be very confused.