The string "x has been added to your Wish List. Click here to continue shopping." can be found in the template Magento/Wishlist/view/frontend/templates/messages/addProductSuccessMessage.phtml
But it doesn't the usual pattern
<?php /* @escapeNotVerified */ echo __('Some string you can translate') ?>
What should I write in my csv file?
Below the template file
<?php echo $block ->escapeHtml( $block->getData('product_name') ) ?> has been added to your Wish List. Click <a href="<?php echo $block ->escapeUrl( $block->getData('referer') ) ?>">here</a> to continue shopping.
Since the question was asked, the template file has been updated to be translatable https://github.com/magento/magento2/commit/624173e59cdbb5f4203ce346b1b53637f32672ef#diff-7586a821ac9c752c277b0c4304885b76