My belief is that the song, even in translation, is copyright protected by the original author.IF you remember, the protection refers to "copies in any form". I know that Song for the Mira (aka Out on the Mira) has been translated into at least 15 different languages, including Gaelic, Mi'kmaq, French, is under Allister MacGillivray's copyright.
As someone who translates material from GAelic to English, I feel it incumbent to protect the rights of the original author of songs.