I don’t think there is any kind of wordplay, but that Queneau points out that the answer from Marceline is just a stereotyped comment, a cliché about being a teacher. She makes this comment because this is the kind of stereotyped statement a French native speaker would do in small talk (in France, a common stereotype is that teachers, as other civil servants, can count on early retirement and high pension benefits).
If we go deeper into literary analysis, it could be seen as a humorous, ironic way for Queneau to criticize how language habits lead us to repeat prejudice and stereotyped ideas.
I would say your Russian translator is certainly right. You have to think of the use of langue here not has the word for language but tongue, as the organ used for speech. I think there’s a clear humor here from Queneau in constructing his sentence as if it was about language (she speaks French) when in fact he refers to cultural language quirks (she speaks like a French would).
You can find many colloquials in French using langue in this way but more explicitly.
- Avaler sa langue
- Avoir la langue bien (trop) longue
- N’avoir pas (point, plus) de langue
- Ne pas avoir la langue dans sa poche.
- Avoir la langue acérée, (bien) affilée, bien pendue
- Avoir la langue épaisse
- Se mordre la langue
- Prendre langue
La langue française means the French language. The sentence is very straight forward- it’s not idiomatic at all. Welcome
to the world of learning la langue française! A little note: When you’re talking about a French language class, the word is masculine- le français. Ex: J’ai le cours de francais le lundi. Le cours, the class, is masculine. You can replace le cours with le français (J’ai le français le lundi or I have French on Mondays.) Note that there is no “e” at the end of the word in this case. However, when you are refering to languages, this is always feminine. J’aime parler la langue française!
Bonus: Putting “le” in front of a day of the week means that you do this activity (in this case- taking a french class) every Monday or whichever day you indicate. If you have more questions, I’m happy to help.