The ApproverMessage for Carts that are awaiting approval are translated when the cart is submitted for approval.

So, if the user submitting the cart for approval is browsing the website in French, the ApproverMessage will always be in French.

The approver, even though they are browsing the website in a different than French, will see the ApproverMessage in French in the OrderApproval List page.

To fix the issue, the CustomerOrder.ApproverMessage should only contain the translation key and it should be translated when displayed to the end user.