I have my AWS assets (DynamoDB tables, IoT devices etc) in EU (Ireland), and if I create a Smart Home skill (configured for English UK only) with the default endpoint pointing to a eu-west-1 hosted lambda, then the lambda is not triggered by Alexa when trying to discover devices (neither in simulator nor via Alexa mobile app). If I create a lambda in us-east-1 and set the default endpoint to reference that ARN, then that lambda is triggered successfully. But that complicates access to my eu-west-1 AWS assets.
If I create a custom skill in the same Amazon developer account, then I can successfully use an eu-west-1 based lambda as default endpoint.
For some reason, both my Smart Home skill and my custom skill show up with devUS tag when viewing in "Your skills" (alexa.amazon.com). From which locale setting does it determine this devUS tag?