Hi,
If you're using non latin characters for the original values, you need to activate the "Non-latin translation keys" setting under the Languages tab of the HikaShop configuration.
Note that this is not only for the custom field values, but for anything you translate in your shop.
Note also that you'll loose the translations you've already done with the setting turned off when you activate it as HikaShop will search for new keys adapted to non latin texts.
Otherwise, another solution is to use the English text as your original values title and enter the other language text as translations. That way, the system will be able to use latin translation keys and it will work fine.