Change the confirmation text when using PMPro and the Email Confirmation Add On.

my_pmpro_email_confirmation_text.php

/**
 * Change the "IMPORTANT!" confirmation text when using PMPro and the Email Confirmation Add On.
 * Add this code into a custom plugin or code snippet.
 * Be sure to change the translated lines below to the language and words you want.
 * https://www.paidmembershipspro.com/how-to-add-code-to-wordpress/
 */
function my_pmpro_email_confirmation_text( $translated_text, $text, $domain ) {
	// Ignore strings for other plugins.
	if ( $domain != 'pmpro-email-confirmation' ) {
		return $translated_text;
    }

	// Message used in the email.
	if ( $text == 'IMPORTANT! You must follow this link to confirm your email address before your membership is fully activated' ) {
		$translated_text = "IMPORTANT! Vous devez suivre ce lien pour confirmer votre adresse e-mail avant que votre abonnement ne soit entièrement activé";
	}

	// Slightly different message added to non-member content messages.
	if ( $text == 'Important! You must click on the confirmation URL sent to %s before you gain full access to your membership' ) {
		$translated_text = 'Important! Vous devez cliquer sur l'URL de confirmation envoyée à %s avant d'obtenir un accès complet à votre adhésion';
	}

	return $translated_text;
}
add_filter( 'gettext', 'my_pmpro_email_confirmation_text', 20, 3 );