Nobody on here is likely going to be admissions counselor and even if they were not likely to be able to speak for the specific schools you are applying to. However, having gone through law school myself I can offer a little insight, but take it with a grain of salt as you should from anonymous internet poster like myself posting on this site or others.
You appear to understand you must disclose this fact. In my opinion the schools will not really care about some french classes. Schools care about your undergrad GPA that is what they have to report to LSAC and U.S. News having a 4.0 in a graduate program usually doesn't help and the same goes for having W's or even F's in graduate school. The 4.0 in the MBA wouldn't hurt you, but it wouldn't help much. Your situation is going to help you, but I doubt it will do much harm.
However, nobody can really say how it will affect, but you absolutely must disclose the fact. When you fill out your moral character application to become licensed for the bar they will look into what schools you have attended. If they find out you left something out your in a deep sh**. If you say I was young and didn't take my French Graduate program seriously nobody is really going to care, but if you lie about it to make yourself look good you have a problem, because the question becomes what else is this person hiding.
I have known people who have had DUIs, spent time in Jail, etc who have been accepted into law school and become licensed to practice law, but they came forward with their stuff. Not taking some graduate french course seriously will not be a big deal as long as you don't hide it. Furthermore, it will have minimal impact on your admission chances as the undergrad GPA is what really matters. Good luck to you.