Change MacOs App language using XCUITest

I am trying to change the Mac OS Apps to a new locale other than English using the following arguments in XCUITest:

app.launchArguments = [
 "-inUITest",
 "-AppleLanguages",
 "(nl)",
 "-AppleLocale",
 "nl_NL"
]

But I get the following message on the console:

Launching macOS application via NSWorkspace while sandboxed. Launch arguments and environment variables may be dropped

The app loads in English itself.

Is there any other way I can change the language of such apps ?

I DONT mind changing the system language as well, but it needs to be done programatically. I tried writing a zsh script to do sudo languagesetup but it requires a restart for the system language to change, which I can't do when my automation is running. If there is any other way please let me know.

EDIT: I open a third party app using the bundle Identifier, like this:

 XCUIApplication(bundleIdentifier: "<app-bundle-name>")

When writing a test, you should use a test plan, which have configurations for the application language and region when testing.

Change MacOs App language using XCUITest
 
 
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