I today discovered a feature tucked away in the System Settings app that I never knew existed: you can set different default languages for individual Mac apps. If you already knew this, then there’s nothing to see here, move right along. But otherwise, this is how it does (and doesn’t) work …
What Is New
Tucked away right at the bottom of System Preferences > General > Language & Region is an Applications section. You can add apps to this and then select a language. In my case, much of my writing is done in browsers, so I’m using two different ones depending on the target language. There is, as I’ve discovered, one important rider: you can only do this with apps that support macOS’s localization/language APIs, so not all apps appear in the list.
I have British English set as my system language, so that applies to Safari, while I have Chrome (which appears in the list alphabetized as Google Chrome), set to US English.
Apple’s US centrism is revealed by the fact that British English is known as “English (UK)” while US English is known as “English – English.

