If you can rule any complication from the cluster, can you replicate that behavior with the SDK on your local machine?

The WCM Core components support an explicit datalayer, but the majority of the computation happens on rendering time, so the complete JSON structure is directly available within the page. See https://experienceleague.adobe.com/docs/experience-manager-core-components/using/developing/data-layer/overv...

Can you please add the "-v" command parameter to curl, so we can see the return code?

The order of the childnodes within /content/myapp  stored in /content/myapp (within the parent node).

This is not possible in a reliable way just by AEM ootb tools.You would need an external system, e.g. a message queue to handle the message passing. Direct connection is probably not reliable enough, as the publishs can be down at any time (and this is not limited to AEM as a Cloud Service, where re...