Multi-Server HA Installation

Hi,
our company have some offices in Europe and Australia. So I like to create a HA Rocket Chat with Servers in EU + AU, include MongoDB replications.

What would be the best way to do this?
Thinking about deploying Dockers for Rocket Chat and the MongoDB Replica Sets on real Servers.
Both in multiple Datacenter across EU + AU.
Then a Load Balancer in a Datacenter in the middle of all Offices to send traffic to the different Dockers.
Good idea or bad one?

Thanks for helping out

Big thing to keep in mind is mongo has one primary. So what ever datacenter the primary is in is the datacenter both will need to talk to for writes. So low latency will be super important