If Firaxis wants to conquer other markets whose culture is not british, they must alert and learn about the culture, history and mentality about the markets they are going to sell their products.
If the fans in Spain Civ games are like me ... (I guess you have to like the story to like this kind of games) ... I assure you that these are people who know quite well the history of their country, the characteristics and extent of the empire who their grandfathers built and also are very proud of this history and empire (the Spaniards are well, you see)
And to such customers, to be robbed what was the motto of their empire, to give also the British,... (For the Spanish people that the opposite happens to you: We know our history, not the british and its colonies, so do not tell them that British also use the Spanish empire motto and in U.S. you associate with them, becouse it don't care. For we it's a robb.)... I assure you it will not going to make any grace to spaniards fans.
Firaxis has screwed to the bottom, So they take it out.
And if not, do not complain if they sold fewer units of Civ V in Spain, than icies in Antarctica.