If you browse the source code of the plugin, you’ll see “return to shop” is used three times in:
includes/class-we-checkout.php:956
includes/class-wc-ajax.php:257
templates/car/cart-empty.php:33
for the first two, the classes – there’s no hooks or filters to change that text. There’s no function that conjurors that text either. It is, as it is. However, you can do a work-around and change it with jQuery on your site. In your theme, or a custom plugin, you can add:
add_action( 'wp_footer', function(){
?>
<script>
jQuery(window).load(function() {
if (jQuery('a.button.wc-backward'))
jQuery('a.button.wc-backward').text("My Custom Text");
});
</script>
<?php
});
As for the third instance, the template – it too will work with the above, but you can hard code this one if you want. In the file itself, it says:
This template can be overridden by copying it to yourtheme/woocommerce/cart/cart-empty.php
So you can do that, and hard code the text as desired.