How to use the Translation ID mapping to link products across language specific feeds
To make sure matching works properly when using multiple language feeds, product id's need to be the same between the different feeds. However, in some cases this is hard to guarantee. With the "Translation ID" mapping you can pick an alternative property that is the same for products between your language specific feeds (for example EAN or SKU).
Enabling the Translation ID mapping
1. Go to "Settings" in the left navigation.
2. Enable the toggle under "Feed -> Enable translation ID mapping".
Mapping the Translation ID
1. Go to "Feed" in the left navigation.
2. Go to the "Mapping" tab.
3. Map your alternative property to the Translation ID property (like EAN or SKU).
All set! Your products will now be linked across the language specific feeds using the Translation ID property.
Documentation