The country specific language text in the Klarna payment method widget can be displayed by configuring the supported locale value in the language code field for the languages available in Localization -> Languages. If the value is incorrectly configured, then the fallback language for widget text is English.
You may be required by your Klarna contract to provide Extra Merchant Data (EMD) for your orders (more information here). If that is the case, you will need to configure this option within the Klarna Checkout module files. After installing the module on your store, create the folder /override/modules/klarnaofficial in your PS installation. Add a new klarnaofficial.php file there, which will contain the necessary data in the form of an attachment (more information here).