Sort of pedantic note - "Breton languge has gaelic roots". No it hasn't. The gaelic (or "Goidelic") languages are Irish, Scots Gaelic and Manx. Breton is one of the other ("Brythonic") branch of Celtic languages, fairly closely related to Welsh and Cornish. The connections between the two branches of Celtic languages are fairly distant.

But there's no need to get hung up about "Celtic" - there's plenty of music from other parts of France which have many of the same musical qualities as much Breton music.