I think the issue is that ST have fixed this defect with a kludge.
AFAIK it’s not normal for the OAuth client (e.g. Harmony) to need to integrate with two provider APIs, depending on user location. This places a burden, and support complexity, onto every single integrating client. Facebook, Twitter, Google, etc do not do this. They manage this within their cloud infrastructure and provide a single URL to clients.
SmartThings do not do this.
If I was building a platform such as Harmony, I’d be having a think now about how and if I wanted to play ball. As SmartThings rolls out to new geographies, presumably this problem just grows, and more complexity is added to each client. Architecturally, this doesn’t feel right.