No offense, but sometimes an annoying aspects of monolingual people(those without substantial second language training, not just ** monolingualism totaritarianists) is that sometimes the only aspect of the concept of a language some of them understand is words.

About 30% each of English vocabulary is to have been borrowed from French. That means the phrase "it's all French to me" in free standing could logically imply that you do have good idea of what is being said. That's obviously never the case.

That's because dictionary vocabulary is just an asset file for a language. It's a major, but still a part of a language. Integrating bunch of words into a language only inflates that dataset.

Dinitrogen tetroxide(N2O4) is apparently called "tetraoksid diazota" in Russian. Do memorizing bunch of those compounds in Russian makes you fluent in that language? I'd very much doubt it.