BS”D
I know of an Algerian Jew named C—istian. In this case the name, not very innocently suggested by Catholic mission hospital nurses who duped his parents, had a very bad effect on his neshomo. He owns or owned a treyf lemehadrin seafood restaurant in Yafo :(.
Yiddish has names that crept in from the surroundings. Masha and Maryasha, probably innocently given to name a girl in memory of a Moshe or Menachem, both come from Maria. Knowing the origin I could never under normal circumstances give those names. However, many of my friends have relatives with those names who lived here in the bad old days under conditions of amazing mesirus nefesh (in particular there are 600 descendants of a renowned “Rebbetzin Maryasha” who were born and are frum today because she kept to the Torah all 106 years of her life despite losing her husband at an early age to the KGB), and it would be a dishonor not to name for these neshei chayil because of their origins.
Since the French names are not as old it is easier to go back one or two generations and find the name that should have been used, but still I understand wanting to name for a relative just as the name was. Nevertheless, when I was in Montreal, it was a common occurrence for a girl with a French name to change it and give out cake on Shabbos to celebrate the change.