How to translate strings in a class (or override) in 1.7.5 ?

[TinoArts]

I've added a new field to the CustomerFormatter.php class:

$format['birthday'] = (new FormField())
                ->setName('birthday')
                ->setType('text')
                ->setLabel(
                    $this->translator->trans(
                        'Birthdate', [], 'Shop.Forms.Labels'
                    )
                )
                ->addAvailableValue('placeholder', Tools::getDateFormat())
                ->addAvailableValue(
                    'comment',
                    $this->translator->trans('We will send you a birthday present every year (E.g.: %date_format%)', array('%date_format%' => Tools::formatDateStr('31 May 1970')), 'Shop.Forms.Help')
                )
            ;

 

I need to translate the "We will send you..." label, but I can't find it in the BO. What appeared reasonable for me was to look into active theme's translations, or "Other translations", but I've looked everywhere and it's not there. I'm not sure I am setting the domain right.

What is the correct way to do this?

Thank you

[arunvishwakarama]

You need to check Admin > Shopparameters > Help.
It should be available there 

[TinoArts]

@arunvishwakarama Unfortunately it is not there as well. I've tried using the search form and also searching page to page, it is anywhere in the back office translations.

By the way, this is a string that displays on the front end (registration form).