If you use English UK then you need to translate English UK translation file and instead of real translation to another language you just replace text to what you need. Got it?
Also, use system folder for the theme translation files https://prnt.sc/gzv0in In other case you will lose translation after theme update. And remove all the other unnecessary translation. You need to translate only xstore theme, you don’t need to translate child theme. I think you did not make changes in child theme that have child theme text domain.