I get different behaviors regarding the default user language when creating a new user in Magnolia:

M 5.1.1 EE (http://demo.magnolia-cms.com)
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Default language is Chinese (Taiwan) - strange selection for my english OS and browsers.

M 5.2-SNAPSHOT without folders
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I get English as default language.

M 5.2-SNAPSHOT with folders
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There is no default language (see screenshot in attachment). If I create that user I can’t login with that account (HTTP Status 500 - Invalid locale format).

In any case:
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• make sure the default language is not Chinese.
• make the language field mandatory in the user dialog (if the language is somehow missing, it should be prevented that the user account can be saved).

Please note that the folder use case might be related to MGNLUI-1505.