given English evolved from Norman French, it's maybe just a local variation than a true invention? fr-GB feels more correct :)

This is more or less completely false. English has an unusually high number of loan words from French (on the order of 10k or so, I think), and this has made the language less Germanic than its historical origins would suggest. But English existed before Norman French arrived in the British Isles, and is still at heart a Germanic language.