Thank you @fialkin.victor for leaving a comment.
It's decentralised, validation of the event is decentralised.
Re: ""The service can decide to throw error and become unhealthy if Event Registry fails to respond."
Since this is happening at the deployment time, it's a good thing. Moreover isn't this true with every micro-service architecture. If one fails, things start to fall down (can be handled in some cases with circuit breaker)
Re: "It looks to me that you are trying to solve the wrong problem."
The problem that I am trying to answer
What are the valid events in the system?
What is the schema/definition of every event in the system?
Rest is the performance implementation