Re: AWS EU issues
Atlassian Cloud is probably Multi-AZ, just the app layers became unhappy with a lack of an AZ because of noted networking issues at the time plus not being able to spin up new instances. Not very tolerant to sudden cloud outages and micro-services being happy with APIs or dependent services being unavailable.
I'm not sure if you can pick data location on Atlassian Cloud, but multi-region across the EU DCs would at least offer some redundancy. Again, multi-region operations in the cloud get extremely complicated.