> Note that french people saying "inshallah" say it as a joke (they use this word for fun effect),
To be fair that is how a lot of new vocabulary ends up in the standard lexicon.
Total tangent there's this thing in Japanese where a word ends up meaning one thing and also its opposite, due to being used ironically. Sometimes the original meaning is lost, sometimes it isn't. Like 貴様 (originally a honorific, now an insult) or 適当 meaning at the same time proper and sloppy.