Hi,
I was going to add the keywords to our translation but guess they already exist in Woocommerce translation files. So the idea is using Woocommerce domain language when echoing those words in the code.
I changed “Customer details” to be translated with Woocommerce but I can recreated that part of that content in your screenshot.
Isn’t that in the checkout? can you take a bigger screenshot.
Also check if customer details is already translated or not.
-Rui