Multilingual folks may have whole other worlds open to them as a result of their skills, but it can also be a point of frustration when using an Android phone — at least, when it comes to voice input. Google Assistant and Gboard have it bad enough, but apps like Google Maps and Chrome use a specific voice input method that rigidly follows the system language setting, turning that multilingual advantage into a pointless limitation.
This problem is straightforward: Not all voice input methods on Android work the same, even though you might think they would. Apps like Chrome and Google Maps use a different type of voice input compared to Gboard or the Google app, and this other older input method simply follows the system language setting, with no fast way to change between languages. So if you have your phone's system language set to English but want to do a search in Google Maps or Chrome in Cantonese or Spanish, you're out of luck without digging in menus, doing your command, and then changing it back.
Different first-party apps use different voice input methods, and the basic "speech input UI" (left) isn't multilingual.
Apparently, this wasn't always the case, either. Reports claim that a previous version of the voice input/search UI followed the Google voice typing setting, though we can't confirm that. Currently, you can set alternative or multilingual voice input languages in other locations, like the Google App, but while that setting is inherited in some other locations, it doesn't apply to this basic speech input interface. There are two potential solutions: You can either change the primary system language setting every time you need to use a different language, or you can use Gboard's voice input as a workaround for text input in the search field, ignoring the built-in voice search tool in both apps with a few extra taps.
Although it's a quite a stretch to call me multilingual, I've tested this myself by setting all possible input language types on my Pixel 5 to both Spanish and English, and though the voice input screen will tell me which language it's set to accept, I can't change it on the fly, and simply speaking (really bad) Spanish results in unexpected and inconsistent results (i.e., Spanish words mixed in with close English synonyms or sounds). The only way to actually change the language for this voice input screen is to change the primary system default language setting. And as far as I can tell, it's not possible to have more than one active or switch conveniently or easily between them.
Contributing to this problem is the sheer number of different places that language settings for different methods of voice input live in Android. There's that system-level setting (Settings -> System -> Languages in Android 11) which controls this input method, the Google app's/Google voice typing setting (Google -> More -> Settings -> Voice -> Language), and the Assistant's setting (Google -> More -> Settings -> Google Assistant -> Languages), all of which affect different things. And this is even ignoring further app-specific language settings.
Tons of language settings (above and below), but none can make that voice search prompt properly multilingual.
In short: The built-in voice input system lacks sufficient multilingual support and follows a setting that's too inconvenient to change frequently. On top of that, there are too many settings that control too many different forms of voice input on Android, adding further confusion to the seemingly arbitrary system language limitation. Maybe it's time for Google to just fully replace the older built-in voice input method with the Assistant (as it's starting to do for Gboard). That's not an ideal solution, since it has its own issues, but it's better than nothing.
We've reached out to Google for more information regarding both this apparent change in behavior, and if any future improvements are planned, but at the time of writing, the company had yet to respond to our inquiry.