<p dir="auto">The exception messages thrown by the user checker don't support internationalization natively :<br>
Symfony/vendor/symfony/src/Symfony/Component/Security/Core/User/UserChecker.php</p>
<p dir="auto">Translating form fields for which translation strings are available in "singular | plural" form fails.<br>
Form translation always uses trans() and never transchoice(). There is apparently no way to tell it to do so. That means duplication of translations or other stupidity to work around this problem.</p>