When I'm creating Item definitions, there is a box to add the name - but I can't see an option for a multi-lingual name. What would be the best way to add this feature?
The Inventory by itself does not support Multilingual because you would usually want to localize the entire game, not just the item names and descriptions.
We recommend using the official Unity localization package, the Inventory has an integration for it so it's supper easy to use:
Localization is a great way to get more exposure on your game by allowing more players to experience your game in different languages and countries. . . .
opsive.com
All items have a unique name, so that name is used as a key within localization table. And instead of directly writing the Item name in the UI, you can use one of the components in the integration to use the item name to find the localized name and write that.