

Lingua franca is technically two words. Lingua franca refers to an old Germanic language lost to language evolution and time, not modern-day French. And using the term to denote a language that is widely understood by different people who don’t all speak it natively is perfectly understood, 20 years ago and today. The admittedly very eurocentric expression fills a useful niche because any explanation in vernacular English inevitably becomes much longer than these two established Latin words. But because it’s Latin the expression is also widely understood on the European continent as well.
I would argue no one could choose one. A lingua franca is silently agreed upon over long periods of time. No committee sat down to make old Frankish the language of trade, modern French the language of diplomacy, and nowadays English the language of internet arguments.
If I had a magic wand though my vote is Klingon as well. Qa’plah.