Since I am using XStore Child now, if the theme is updated later, will I lose my translation?
Also, the Po. files (https://ibb.co/TbfT86h) were created by me just an hour ago, I did not make any change in these 2 files. Since I selected the wrong location (Languge/loco/theme/xstore) when I was creating it, can I just delete them and recreate a new one? Will that causes any negative effect?
1) You need child theme translation files only in case you added custom code in child theme that includes localization functions, for example echo _n( '%s star', '%s stars', 1 ); etc.
If you don’t include in child theme any strings that require translation you don’t need translation files for the child theme.
2) You can use one of the directories:
either /wp-content/languages/themes/ or /wp-content/languages/loco/themes/ It’s ok. But don’t use /wp-content/themes/languages becasue you’ll loose translation after theme update.
Also, after any theme update, we would recommend you to Sync translations http://prntscr.com/npu8x3