Thanks for the quick response. I have automatic updates turned on using the Jetpack plugin. This needs to be turned-off, if the Tribes product customizations are to be done in the main theme folder. The WooCommerce Theme Customization Plugin is merely a skeleton plugin that moves customizations of styles.css, custom.js and functions.php to a plugin folder so that future updates of the StoreFront themes do not end up overwriting the customizations.
My recommendation would be to have a similar approach outside the main theme folder for Tribes plugin customization in the future.
For now, I have turned off automatic updates of the WooCommerce plugin and the StoreFront theme and I will backup my Tribes customization before applying an update.