Please, please do not import foreign words that describe mundane things your language does have its own words for.
So, you’re writing a cute story about, say, an American couple travelling through Provence. It’s all slightly exotic, and very characteristic, and you want to describe that. You want to convey the spirit of the thing. I get that.
But if you’re going to write how “they entered a lovely little épicerie where elderly patrons ate their customary fromage and saucissons hanged from the ceiling”, then you are not including any interesting local colour.
You are trying very hard to exoticise very mundane things because you failed to observe any actual local colour. You are yelling “they were in France, btw!” and going “have I mentioned this was in France?” and generally being silly and pretentious.
There are totally valid cases of foreign words introduced into prose. These are usually words that the main language does not have in its repertoire. So while it makes sense to say that they had apéritif, it does not make sense at all to say they had a “repas” when the word “meal” is perfectly available.