How to Translate Custom CMS Page Settings

[ssi-com-pl]

Hi! How to translate custom fields added to CMS Layout / Page settings popup?
'translatable' => true not work

Event::listen('cms.template.extendTemplateSettingsFields', function ($extension, $dataHolder) {
    if ($dataHolder->templateType === 'page') {
        $dataHolder->settings[] = [
            'property' => 'subtitle',
            'title' => 'Subtitle',
            'type' => 'text',
            'translatable' => true
        ];
    }
});