The best way to customize a template file from a third-party module is to create a new theme that inherits from the parent theme and override the template file in the app/design/frontend/Custom/Theme/Vendor_Module/templates directory. This way, the customization is isolated from the original module and can be applied to a specific website or store view. Creating another layout file or a new module would not be as simple or flexible as creating a new theme. Reference:Frontend development guide, [Create a theme], [Theme inheritance]

To override a layout XML file from a parent theme, the developer just needs to place the modified file in the same path relative to the layout directory of the child theme. In this case, the file would be app/design/frontend/ExampleCorp/orange/Vendor_Module/layout/catalog_product_view.xml. The override directory is not used for overriding layout files, but for overriding templates and web assets. Reference: [Layout instructions], [Override templates and layout files]

To create translations for a theme, the developer needs to place the translation files in the il8n directory of the theme. The translation files should have the format <language code>_<country code>.csv, such as en_US.csv or fr_FR.csv. The etc and translations directories are not used for storing translation files. Reference: [Translations overview], [Translate theme strings]

The theme.xml file is responsible for specifying the parent theme of a custom theme. The file should contain the element with the value of the parent theme's directory, such as MagentoMuma. The view.xml file is used to configure the theme's images, fonts, and layout. The registration.php file is used to register the theme in the system. Reference: [Create a theme], [theme.xml]

The favicon can be added to the <your_theme_dir>/Magento_Theme/web/ directory of a custom theme. The favicon should have the name favicon.ico and replace the default one from the Magento_Theme module. The <your_theme_dir>/web/ directory is used for storing web assets that are not specific to any module. The <your_theme_dir>/assets/images directory does not exist by default and is not used for storing favicons. Reference: [Add a favicon], [Theme structure]