I am working in Project Online, and I have already a PWA instance that has been created by default with English but when I changing the language settings and add Arabic as an alternative language it's not switched to the alternative language automatically and still shows with the default language.
To reflect the alternative language in Project Online, you have to adjust the Display Languages in the Language and Region settings for the current user.
To show the PWA instance in Project Online with your alternative language, not the default language you have to do the following:
Show Advanced Settings
My Display Languages:
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