What After Eight may be decrying is the tendency for French from an American mouth to sound like suburban pretentiousness (like poor old Charlotte Haze in Lolita).
I have to admit that, between "Sondheim's oeuvre" and "Sondheim's works," I'd opt for the latter, just for the simplicity and lack of fleurs.
But "works" is so vague- you could be referring to his heroin spoon, needle and tourniquet. Oeuvre is the word: The works of a painter, composer, or author regarded collectively: "the complete oeuvre of Mozart".
And while I pronounce it perfectly (my eight seasons as the dramaturg of the Paris Opera pretty much guarantees that), even if I didn't, on the internet, no one can hear you mispronounce.