Nobody would disagree that everybody speaking the same language on the frequency would improve situational awareness
Alberto disagrees apparently.
So, it is not necessary to always speak in English, nor in your native language, you just have to use the brains god gave you and know when to use which. Its that simple and there is no argument to this.
I think correct terminology and readbacks are important in these bilingual envoronments as well. So many people read back all sorts of rubbish that is not required and add their own little tid-bits to each transmission as well.
Discipline is the key. Transmit only what is required using the correct terminology and a lot of the problems are solved.