I lived with a guy from Cornwall last year, he could speak a little Kernow and I could even understand a bit of it
(me being a native welsh speaker). He told me about the independance movement down there and about MK Meybon Kernow which translates to (i think) sons of cornwall. The only problem youve got is that there are 0.5 Million in Cornwall but only 300 people who can speak the Language to a fluent degree. On the upside it is now being taught in primary schools. Language isn;t the be-all and end all, but if you compare Scotland for instance, they were incorporated in 1707 but still got to keep a fair few bits of their establishment and importantly their Law. Contrast this with the Welsh who in 1282 got annexed by the English and we lost everything (nearly) we lost our legal system and sentenced to hundreds of years as second class citizens enslaved by the English. There was one thing they couldn't take away from us, and that was the Language, but we nearly lost that, and what saved it was a simple book
you may have heard of it, the bible which was translated by William Morgan in 1588.