Noëlle is
not a made up "Americanized" French name.
It was used mainly in Middle Ages, just as other Christian/Catholic feasts (
Toussaint, Tiphaine, Noël...) and just as in other European languages (Nadal/Nadala in Catalan, Natal or Epifanio/Epifania/Epifanía in Spanish, etc.). After this age, the name (and the masculine Noël) fell in popularity and it was recuperated in 20th century for use (also in the compound Marie-Noëlle).
It had a moment of splendour in '40s-'70s, with a zenith year in 1949, with 1,095 new-born girls named Noëlle.
At the begin of 2006, a total of 24,453 girls
in France were named Noëlle.
Lumia
http://onomastica.mailcatala.com