The solution for translating the sprox labels was setting them explicitly with the __field_widget_args__ attribute of the ViewBase class. The following snippet from one of my projects shows an example of this:
class NewUserForm(AddRecordForm):
__model__ = User
__required_fields__ = ['password']
__limit_fields__ = ['email_address', 'display_name', 'password', 'verify_password']
__base_validator__ = user_validator
__field_widget_args__ = {
'email_address': dict(label_text=l_('eMail Address')),
'display_name': dict(label_text=l_('Name')),
'password': dict(label_text=l_('Password')),
'verify_password': dict(label_text=l_('Verify Password')),
}
email_address = Field(TextField, All(UniqueValue(SAORMProvider(DBSession),
__model__, 'email_address'),
Email(not_empty=True)))
display_name = Field(TextField, NotEmpty)
password = String(min=6)
verify_password = PasswordField('verify_password')