It looks like this is an issue that can be fixed either by changing the source data or config on your server side,
Changing the source data part(values in AAD) is straightforward enough.
If you would like implement logic that says "If a user has USA, send US, if they have CAN send CA, etc.." then you will need to do that yourself.
You can use the Switch function for that.
However there are no current built in methods in Azure for this right now. I apologize for the inconvenience, I suggest submitting your feedback in regards to this here : https://feedback.azure.com/forums/169401-azure-active-directory and if there's enough community support the product team will put this on the roadmap to implement in the future.