For one, Latin has more fancy rules than French. I guess the subjunctive is probably something English speakers might consider fancy, but Latin has that too. Latin has more times that are conjugations of the core verb (rather than needing auxiliary verbs), has grammatical cases (like German, but two more if you include vocative) and, idk, also just feels fancier in general.
I’ll admit it’s been years since I actually read any Latin and that I only have a surface level understanding of all languages mentioned except for French, but this post reads like it’s about the stereotypes of the countries rather than being about the languages themselves.
Meh, as a native Dutch speaker auxiliary verbs feel really utilitarian to me, and not particularly fancy - like you said, that’s highly subjective.
As for cases, I didn’t say Latin or German had the most, but just that I think they’re fancy and that Latin has them while French doesn’t.