Cormac McCarthy is decently translated (for having read him in both English and French) and is well known. But for the average French litterati, American literature harks back to Hemingway, Steinbeck, Salinger, Burroughs, Capote, Nabokov and so on much before McCarthy. Toni Morrison isn't well known here yet, if only because her writing is embedded with Afro-American reality which is off-phase with Europe culture. For the same reason you'd hardly hear about Ralph Ellison in France if you're not in circles aware of post-colonial African diaspora writing.

To the same token, French authors who make it across the Atlantic aren't always the most valued here.

Yep, I had never heard of Derrida until I read a mention of him in an American Physics journal of all places.

It's interesting Nabakov is thought of as American. Yes, an American citizen beginning age ~46 (in 1945) but born in Russia, wrote in multiple languages, lived much of life in Europe.