Thank you very much for your tip! I discovered lots of other strings to modify as well, that's great!
I was able to change the "Continue shopping" label where you told me and it changed the link in the cart when products are listed. However, when the cart is empty, the button still shows "Continue shopping": https://fm4uxdtoso0ldex6-34503590019.shopifypreview.com
This must be somewhere else.