Well, Yoko, Vic and Pol certainly speak english. Consider this: In "Le dragon de Hong Kong", Yoko tells Vic and Pol that Rosée only speaks Chinese (I don't know what is the translation for "mandarin"). But in "L'astrologue de Bruges", Yoko tells Mieke that Rosée only speaks Chinese and English (so she learned English meanwhile). I assume that she uses english to communicate with Vic, Pol and maybe with Yoko too. I would be curious to know how many langages Yoko knows. She knows German, French, English, Chinese, Japenese.. and what else? That's already a lot.

I was wondering why we are naming Emilia "Emily" here. I dont think her name has been translate.

Since Emilia can speak with Rosée... maybe we could say that there is a good probability that Emilia speaks English with Yoko. But maybe Rosée has learned French using the translator.