^ That's so great! Congrats!!!
Hey! Sorry for the late response. I thought the same! So I did just that, though two of the interviews I've had ended up only having one brief question in French. The third one was all in French, but the email said it would be and that it wouldn't be more than 10 minutes (and it wasn't, it was like five). So all the French Qs seemed like quick comprehension tests. The harder questions were all in English.
If it helps anyone/future people, the first I had was about an hour and was specific questions about work background, research interests, undergrad classes/school pedagogy, questions about close reading style, and he also had my file on hand and asked about direct parts of my sample, classes, etc.. Also some more interesting questions like 'I was reading about so-and-so event, what did you think about that in this context?' But in a pretty conversational way, not like a quiz or anything. The second interview I had was about 20 minutes and they asked broad research questions (more along the lines of 'so you're interested in this? How does it relate to previous coursework?' than 'tell us specifically what you want to study and why'). The third was the French one and was pretty general - Why do you want to pursue a doctorate? What do you want to study? Did you spend time abroad? They were stressful for obvious reasons and I totally messed up all my answers, but in retrospect, I think they were less intimidating than expected (no questions about authors, eras, theories, etc.). The professors were all very nice and pretty conversational.
I hope you've had good news!!! Best of luck to you!!