1) Looks like this field is added by an additional plugin. Please check the translation of plugins on your site. Without access to your dashboard, I can’t say more.
“SKU” and “categories” relate to our theme translation.
I would recommend you to synchronize translations.
Make sure you placed translation files of the theme into the /wp-content/languages/themes/ folder with correct names (language name and xstore theme suffix, e.g xstore-de_DE.po, xstore-de_DE.mo).
Button Sync (Loco Translate plugin http://prntscr.com/glemdq) allows you to synchronize your translation file with pot file. Then you will be able to translate untranslated strings.