This is a UX issue. The deployment-overlay uses --deployments as the argument to specify the deployments affected by this command.

In the available help, we can read that this argument is to specify the deployment runtime names:

[standalone@localhost:9990 /] help deployment-overlay
SYNOPSIS
....
 --deployments       - a comma-separated list of deployment runtime names that,
                       depending on the action, should be linked to or
                       unlinked from the specified overlay.

                       NOTE: In non-interactive mode the list must be surrounded
                       by square brackets e.g. [test.war,*-admin.war].
....

However, when using it with an unknown runtime name, the command succeeds silently, without providing any feedback describing that the current runtime name is not available:

[standalone@localhost:9990 /] deployment-overlay add --name=test-overlay --content=WEB-INF/beans.xml=/tmp/beans.xml --deployments=unknown-deployment
WARNING: redeployment is required on deployment [unknow-deployment]

Or even completely silently when using the --redeploy-affected:

[standalone@localhost:9990 /] deployment-overlay add --name=test-overlay --content=WEB-INF/beans.xml=/tmp/beans.xml --deployments=unknown-deployment --redeploy-affected
[standalone@localhost:9990 /]

That could be an advantage if you want to prepare deployment overlays in advance before deploying any affected application, but it can lead to the false assumption that your overlay was applied when you have used your deployment name instead of your deployment runtime name. In such a case, your deployment overlay will never be applied.

At least, it would be better to report a message, a kind of confirmation, whether the deployment-overlay will be applied or not to any existing deployments