This is less of an exploration of Tana French's work, than a post giving permission to do what she does: change the geography of a real place if it suits your story and don't apologize for it.
All of French's novels take place in Dublin, but if you tried to follow her street directions (kinda like people do for James Joyce's Ulysses on Bloomsbury Day) you will get hopelessly lost. Because the places don't exist.
What does making up geography do for you as a writer.
One word: FREEDOM.
You can do what you want, when you want, and you don't have to reference maps or your own memory, if your setting happens to be a place you know and love. It saves you endless back-and-forth checking. It allows you to put obstacles in the character's way. It allows you to make the setting your own.
So, if you've been stuck in a real city or other location and have rearranged whole plot points because of the plain-old existence of certain things in your real-life setting, feel free to move some stuff around. Add a mile or two. Create a detour. Imagine a short-cut. Or extend a highway. If you do it in a convincingly descriptive way, no one will bat an eyelash.
And you can just add a note, like French does at the end of Faithful Place:
"Faithful Place did exist once, but it was on the other side of the River Liffey -- northside, in the warren of streets that made up the red-light district of Monto, rather than southside in the Liberties -- and it was gone long before the events of this book. Every corner of the Liberties is layered with centuries of its own history, and I didn't want to belittle any of that by pushing an actual street's stories and inhabitants aside to make way for my fictional story and characters. So, instead, I've played fast and loose with Dublin geography: resurrected Faithful Place, moved it across the river, and added this book into the decades when the street doesn't have a history of its own to be pushed aside.
As always, any inaccuracies, deliberate or otherwise, are mine."