Currently, the S3 region property in the CBAS UI is a dropdown list, which forces the user to select one of the S3 supported regions. Other S3-compatible storages can support non-S3 regions.
The user needs the ability to either select from the dropdown list, or manually input a region name. Such capability now is only possible through using the REST API or the CLI.
MB-44112 [CX] External links fail for non-S3 regions