the helper method plone.app.vocabularies.metadatafields.get_field_label used here https://github.com/plone/plone.app.contenttypes/blob/master/plone/app/contenttypes/browser/folder.py#L161 doesn't translate all catalog metadata fields (eg "Title" or "Image"). Using the MetaDataFieldsVocabularyFactory instead would translate unmapped field labels as a fallback.
result on 6-classic.demo.plone.org:
