Hi,
As per the Dialogflow limitations, When a non-default region is selected integration feature is not available currently.
=> As such a Feature request[1] has been submitted with the DialogFlow engineering team to address the concern. You can star [2] the report [1] to receive updates directly from the product team.
Also, I would recommend up-voting on the issue by clicking on the `+1` icon indicated above the title of the request[1].
Thank you.
[1] https://issuetracker.google.com/issues/183685826
[2] https://developers.google.com/issue-tracker/guides/subscribe#starring_an_issue