I can also confirm that boutade is not commonly used in the English language. I've seen it in print before, but usually when the author is inclined to pepper prose with the odd bon mot. If you've already expressed that, as a soi disant writer, you feel a certain joie de vivre at just getting up and oh, mon Dieu, you've just found the perfect nom de plume but, no, quel dommage! it sounds too much like your dear tante's name...well, then you might feel the need, peut-être, to use the word boutade as part of your répertoire.

As for author intent, I am in complete agreement. My primary objection with Camilla's line of reasoning is that it strays into exactly the fuzzy territory you mentioned in your réponse.

Pardonne-moi, s'il te plaît. (Based on Russian rules of familiarity I feel I can use the tu form...but please correct me if that it too presumptuous) I'm having far too much fun now that I've gotten started on Franglais.