Scan for strings: Navigate to WPML > Theme and plugins localization and ensure "WooCommerce" is selected. Click to scan it for strings.
Scan the page: Visit the cart page in the front end to register any new strings.
Translate the strings: Go to WPML > String Translation, select the woocommerce-wc-cart-block-frontend domain, and search for the untranslated text (e.g., "Proceed to Checkout").
Add the translation: Click the pencil icon to add the translation and save.