This diagram reflects a project I’ve worked on in the past actually. Not so much an answer to your immediate problem @paulhobbel, but Axon has introduced subscription queries in Axon 3 to keep your instances up to date automatically. Axon Server automatically deals with those in a distributed environment as well, ensuring you can leave all the routing in Axon’s hands.
I understand you are comfortable doing it yourself. If so, by all means. Just wanted to point out that I assume subscription queries would be the up-to-date solution nowadays.
That’s my 2 cents.