Point is that if you want to create filter by the custom taxonomy then you don’t need the sidebar file because we use custom widget – 8theme Brand filter widget. So, if you want to have the similar filter you also need to create the custom widget (check this tutorial, for example, https://www.wpbeginner.com/wp-tutorials/how-to-create-a-custom-wordpress-widget/ ) and probably to use the custom script in addition, to make it work with the Ajax.
Use child theme for any kind of customization and never change the parent theme or XStore core plugin files because you will lose your customization after theme or core plugin update.
If you need help with additional customization you can submit request here.
