Zeebe only provides an automatic retry (with exponential backoff) for the polling for new jobs for the java client. However, it does not provide any ways to retry sending a command from the client. You’ll need to use some retry mechanism for the language you’re using.
Yes, the Node client implements automatic retry to deal with transient conditions. In Java, I would wrap the client with a facade and put the retry logic in there. This is effectively how the Node client does it - it is a wrapper around the gRPC API with logic for things like retries and authentication.