The “evidence” for this is pretty simple for anyone who has lived and learned different languages. It's the reason learning ancient Greek was for a long time a necessary step for European's elites, since the Roman Empire - the language was deemed to be a better medium of thought. For instance, there are multiple declinations of the word "love", with, for each, a subtle flavour, that is difficult to replicate precisely in English, and even harder in other languages :
https://en.wikipedia.org/wiki/Greek_words_for_loveA language that insists a lot on the logical aspect of the sentence, such as French, will lead the speaker to think more logically. A language that makes it easy to create new words, such as German, will help the speaker to create new concepts.
A speaker of a language where time is represented linearly (say, Indo-Europeans), will think differently about it, compared to someone who speaks a language where the concept of time is much more relativistic. There is a plethora of literature regarding “African time” and why westerners have a hard time to understand African's view of punctuality because of this.
The same goes with personality, it's common that people have different personality depending on the language they speak! I'm personally much more polite in English, as the use of conditionals is much easier than in my native language (French). Some languages are also meant to be spoken differently depending on the sex of the speaker - Japanese comes to mind.
Does that mean that some things can't be translated? Not necessarily, but there's always something lost in translation, along with friction. No language is also “Turing complete”, and there's not a pure 100% overlap between every language. For instance, Estonian has no native word for art because of its peasant origins, and had to borrow the German "kunst"!
There's also a “bandwidth” aspect - some languages are slower to convey information, while others are faster. French is one of the fastest, and if you know French top-engineers, you know that they tend to speak FAST on top of this! ;-)
As such, if your mother tongue is a good language to do science (French) in, and you're discussing with a fellow native speaker, it's preferable to speak in it rather than in English. It's also much more comfortable, and the cultural proximity allows for a better work atmosphere and relationships. Which probably leads to better-performing teams as well.