For most of my apps, I have very little idea on their region aside from their login IP origin, and we get a high level of multi-region travels (like conference organizers). I'd encourage you to transform the notion of a tenant transfers from a 'major decision' to 'assume users will/should switch to closest tenant login'. It looks like your platform already allows this move-tenant-on-login approach, but I'd love to see more docs and more tests around that use-case.
update tenants set deployment_mode = 'shared' where name = 'customer 2';
The architecture includes proxy layer that handles routing and maintains the connections, so we believe broken connections are avoidable.
If they travel a lot, you may want the data in one location (although it still depends, moving data is often faster than flying to a different region).
Tenant placement is especially great if their location has data residency requirements. We discovered that companies with many EU customers need this.