Updated compatibility file for WCML (https://wordpress.org/plugins/woocommerce-multilingual/) used to get Klarna Checkout payment gateway (https://woocommerce.com/products/klarna) to work with WCML/WPML multi currencies in WooCommerce.

class-wcml-klarna-gateway.php

<?php

class WCML_Klarna_Gateway{

    public function add_hooks(){

        add_filter( 'wcml_multi_currency_ajax_actions', array( $this, 'ajax_action_needs_multi_currency' ) );

    }

    function ajax_action_needs_multi_currency( $actions ){

        $actions[] = 'klarna_checkout_cart_callback_update';
        $actions[] = 'klarna_checkout_coupons_callback';
        $actions[] = 'klarna_checkout_remove_coupon_callback';
        $actions[] = 'klarna_checkout_cart_callback_remove';
        $actions[] = 'klarna_checkout_shipping_callback';
        $actions[] = 'kco_iframe_shipping_option_change_cb';
	$actions[] = 'klarna_checkout_order_note_callback';
	$actions[] = 'kco_iframe_change_cb';
	$actions[] = 'kco_iframe_shipping_address_change_v2_cb';
	$actions[] = 'kco_iframe_shipping_address_change_cb';

        return $actions;
    }

}