I've tried google cloud run and I have it running in a minute with just "defaults".
Google Cloud console -> Google Cloud Run -> Deploy Container -> Create Service
container image url : jsreport/jsreport:4.8.0-full
Allow unauthenticated invocations
Container Port: 5488
This works for you as well? The problem is the custom image with templates?
I'm not sure if this is relevant to the original question, so maybe you'd better move to the new topic.
