Is this really so hard? You could fix this by just allowing us to use some variants from the CSV file more than once. For example, using the product name or description for the customs description. Or using the price to reflect the price in the declaration.
Beyond that — yes… you should be able to map all the customs fields to a CSV upload. This is a massive time suck if you have multiple international orders. Especially since the update makes the customs form even harder to navigate to. Each time you click on a new order, it resets and bumps you back up to top. So that means every declaration you need to do, you have to click on the order— scroll down the right side. Populate each one manually— then click on another order and repeat.
Versus mapping it all which means you don’t even have to think about it.