Thank you for reporting this issue, and for the feedback. The error message that you mentioned isn't related directly to the Translation API, and is potentially related to your development environments (network configuration).
Google Groups are reserved for general product discussion, StackOverflow is for technical questions whereas the Issue Tracker is for product issues (such as unexpected/ incorrect behaviors) and feature requests.
For this reason, since the result is unexpected I’d advise you to open an issue to the Translation API issue tracker [1], in order to officially file this issue and you’ll be able to get updates directly from the product team.
Also, you should ensure that you're using the latest Cloud SDK version [2], and Python client library [3].