function wcfm_custom_2022_translate_text( $translated ) {
    $original_text = array('<b>%s</b> successfully registered as <b>Affiliate</b> to our site.');
    $translated_text = array('Your translated text here');
    $translated = str_ireplace( $original_text, $translated_text, $translated );
    return $translated;
}
add_filter('gettext', 'wcfm_custom_2022_translate_text');
add_filter('ngettext', 'wcfm_custom_2022_translate_text');