The "cts" mark for Karat was not exclusively used for the French market (where 18 cts was common) but was widely used on English nibs too, especially Conway Stewart. So the pen is rather for the European market, not just for France.
I have a similar Eversharp Symhony with adjustable nib and Deluxe cap.
Interestingly, the Eversharp double check "√√" logo appears on the nib slider, on the feed and on the barrel (see pictures below). this suggests that these parts do belong together eg that the adjustable nib on these Symphony pens is not a replacement.
Edited by joss, 13 October 2017 - 09:51.