I don’t know what you are talking about re multi-lingual Europeans - I have worked with many, whose English is flawless, they are obviously are fluent in their mother tongue, and I have been at meetings and conferences with them where they have spoken for hours in a third language. None of them depended on listeners who can understand.
No one who speaks only one language can be considered cultured.
Those are seriously important languages in the modern world and everyone of them is more widely used than French.
Speaking of French, do you read well in documents written in Gallo? There used to be a number of spoken versions of Gallo and all the kings of England spoke it ~
As I said most people learn one language well ~ but there are a large number who can learn to read just about any written language in relatively short order. With today's computer assistance my own reach has extended out to many dozens of languages ~ but that doesn't make me fluent in them.
BTW, fluency is usually determined by a TEST with STANDARDS OF PERFORMANCE ~ but being able to order a beer or declaim for hours in a second language regarding a technical field does not equate to fluency.