Here are my observations about working with SuiteCommerce Standard version upgrades. 1) we need to update our custom theme that is based on the standard base theme every 6 months. 2) you need a copy of the base theme of the current version (2018.1 in our case) and new version (2019.1 in our case) so you can diff them to find the changes. 3) Apply the diffs to your current theme after SuiteCommerce Standard bundle is updated.