I think that discounting Galicia as a Celtic nation overlooks part of the preserved culture of the people. I have a friend from there who has played in many Galician groups and they always have played music that is more Celtic in nature. Furthermore he identifies himself as Spanish, but is a frequent participant at Celtic festivals, because of his self-identification with Celtic culture.
So while I definitely believe that language has a large impact on culture, in this case I don't believe that poor Galicia should be totally counted out.

And as for France, I don't think anyone was calling them Celtic. They are just the home of Brittany/some Galicians.