Translation files update
If you update theme you will also need to update theme translation to keep it up to date and avoid problems with untranslated strings.
Update translation using poEdit:
1) Open .po file and press Catalog > Update from POT file
2) Choose the pot file that is located in xstore/languages/ folder on your site.
3) Save changes and re-upload translation files to your site.
Update translation using Loco Translate plugin:
1) Edit translation and press Sync button
2) Save translation.