Every author must decide what is important to him or her in an editor, but in these days of electronic communication, honestly I do not think it is important to seek a local editor unless your book is specifically related to something of local interest. Even in that case, you may benefit from the perspective of someone who does not have all the local knowledge it can be easy to presume, so that you can prepare your book for a wider audience.
Obviously there is a big difference. I actually started with screenplays (with some mild success) partly due to hearing that as long as you have a good story, the grammatical errors won’t be a big deal. Well, that was not true. Maybe if a producer liked the story or I was already established but every contest I entered always came back with feedback about the grammatical errors. Even if I won or placed as a finalist, I always received critique on that. Very little is spelling error, it was more about structure, etc.