Hello,
You are right about the regions. As per the help center article about
available regions and zones, us-east2, us-east3, and europe-west5 regions seem to be not listed as available regions/zones for now.
That's being said, my understanding of how exactly(reproduction steps) you were calling the API services could be wrong. So if you could reproduce the issue from your end, I would strongly recommend you to report it as a defect using the
issue-tracker. While opening the report, make sure that you have included all necessary details such as steps you have followed, documentation used, expected output, the error message you are getting, etc.. in that report.
I hope this helps.