If I use the Grim dawn stash to store all items found in the game, as well as the localization file. What will happen to the objects stored in the database when localization change, for example, change one letter or add the property of the object. Can I transfer them to the game? And if the localization is updated, need to do the import on settings tab?
The item descriptions are stored in the GD Stash database, so if the localization changes, you need to import again to have the changes reflected in GD Stash.
You can always transfer items between the game and the tool, even if the localization is out of sync, as the description is not part of the item information that is being transferred.
If there are new affixes or items, which need entirely new translations, you need to import again in any case, so the tool becomes ‘aware’ of the new affixes / items.