2. This text should be available in the translation of the XStore Core plugin.
Go to Loco Translate > Plugins > Core plugin > New language and create the translation. If the translation is already created there, you need to update translation files – https://xstore.helpscoutdocs.com/article/103-translation-files-update then you will be able to translate untranslated strings.
3. Please read this article https://xstore.helpscoutdocs.com/article/30-base-theme-translation You need to place translation files of the theme into /wp-content/languages/themes/ folder with correct names (your language name and xstore theme suffix, e.g xstore-fr_FR.po).
