I'm a bilingual Japanese/English speaker. Searching Google's search languages to English and Japanese causes the following:
- Random Japanese words show up in things such as Google Maps, even though my display language is set to English.
- Japanese results will be prioritized over English ones. For example, If I search for "the beatles", it will show the Japanese Wikipedia page as the top result before the English version. For some sites (like Discogs) only the Japanese version of the site will show up.
If just set English as my search language, searching in Japanese can bring up results that are entirely in Chinese, even though I've set my preferred languages as English and Japanese (in that order).