I also have the same problem. The text ‘Buy Now’ doesn’t get translated in german. In my case, the behaviour is a bit random. The text get translated sometimes in Firefox, but it doesn’t get translated in Chrome. I have tried in different and in different browsers but no result.
We are now using old Paypal Standard, but wanted to move to the newer version. There is another problem we encountered in this version. When user click on the Buy Now button, it doesn’t check the required fields. It redirects to Paypal even if the required fields are empty.
Hoping to get these problems solved soon, so that we can move to the new version.