Google's voice recognition works well when it's English plus one other language. If neither is English (eg. Japanese + Cantonese) it doesn't work at all. Neither does the triple combination of English + Japanese + Cantonese work, even if explicitly specified in settings.
I always select English as my default language in my phones, some years ago if I wanted to call someone with a Spanish name saying something like "Call Ramon Hernandez" or asking for directions "Take me to Periférico de la Juventud" I used to had to fake an American accent. Today I don't have to do that anymore, I can speak natural Spanish and then it can understand my Mexican accent when I speak English. So it's not just improving in bilingual queries, they have focused in accents and mispronunciations.