I've build a multilanguage-site (NL & FR, using translatable) and I created a custom login form

class CustomLoginForm extends MemberLoginForm 

Everything works fine, but when a visitor selects the French locale, the login-form part is always displayed in Dutch (NL). The header & footer are all in french, and even $Locale outputs 'fr_FR'

In page.php Page_Controller::init():

if($this->dataRecord->hasExtension('Translatable')) {
    i18n::set_locale($this->dataRecord->Locale);
} 
// Set locale for PHP, dates etc;
setlocale(LC_TIME, Translatable::get_current_locale() . ".UTF8");

Even when I set the locale to French in _config.php, the form is still shown in Dutch;

i18n::set_locale('fr_FR');

I ended up setting the locale again within the custom loginform file, which works (at least a preliminary fix);

<?php 

// Set locale again, for some reason the locale from page_controller isn't adhered to...
i18n::set_locale(Translatable::get_current_locale());

class CustomLoginForm extends MemberLoginForm { ...

Is this the way translations are supposed to work? Or have I done something wrong?