Nomad's boss, BigN, made me read the post till the end, and I found something with which to disagree:

Alright, so, you have Nodame, a notorious screw-up, in a foreign country. Obviously, she’s not going to speak the language at first, so, you have an episode of grace in which to get her to learn the language, which they did in an amusing way. So far so good. The problem shows up, when Nodame uses some random French phrase. I get that it’s funny and random, but, wasn’t she just talking in French? What the heck? I know it’s a tiny thing to cause such a big reaction, but, it annoys the hell out of me.

I don't recall Nodame ever using a French phrase while presumably talking to anyone in French. Of course, we cannot hear the actual language, so we use the identity of her interlocutor to identify what it should be. Naturally she talks in Japanese to Japanese, and in French to everyone else. There's some ambiguity when both Chiyaki and someone else is in the conversation simultaneously [^1]. Unfortunately, since I did not find any of those French inserts particularly noteworthy, I did not, well, note them. So it's possible that a scoreboarding error existed (e.g. Nodame doing it while talking to someone other than a Japanese person), Nomad caught it, and I missed it. However, he does not refer to anything specific, and the only specific case I remember is something different — and explicit signifier of Japanese: in ep.05, Kuroki wonders if it is French when Nodame exclaims "MUKYAA". Makes sense, doesn't it?

I found it more magical how Nodame studied French. It took me years to get English to a useable level... Sure, perfect ears and everything, but still it was difficult to swallow. Oddly enough, Nomad explicitly mentioned the Nodame's magic acquisition ability as something acceptable by comparison with short French inserts.

[^1] I always find it extremely rude when Mexicans yap away while we're right there, and so I made a point to use Russian and Japanese when talking to family members when it happens, just to balance the situation. Otherwise, it's strictly English when anyone else can hear it. Ditto at work, I never talk in Russian to Russian colleagues. Some of them even get miffed about it. But better them thinking that I'm too proud of my English than someone thinking we have an identity-based cross-group in a professional setting. Honestly I have no clue what Japanese rules of politeness and propriety dictate to Nodame when she addresses Chiyaki in public. It can go either way.