Appliance locales settings is not changing the plugin locales, it always sets English-US

Hi Team,

As we are going through Appliance settings, we tried to change the language to French/Japanies, looks like its not updating plugin UI locales properly.
We have 2 locale files messages_fr.properties messages_ja.properties , if we change the browser settings, locales are updating properly in our plugin UI but when we change the appliance locales settings, it is always translating to English.

What is the locales preference here? will crowdin plugin look for Browser settings or appliance settings ?

Is there anything we are missing here? apart from the locales files do we have make any other code change ?