That link is about ElasticSearch, not searching for AWS resources. It doesn't seem related at all.
https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/Using_Fi...
The point is that pockets of AWS are recognizing a need for global resource search.
But we are totally taking note of your request for cross-region search :) It's valuable feedback to us and why we're posting here.