I have spent a ton of time and combed through the docs to figure out this. My custom built react component is not displaying in the editor, ever. It is showing up on the http://localhost:4502/content/wknd-events/react.model.json and in the CXR/DE. Feel like I have tried everything and I am not seeing any resources for debugging this/ a workaround. The custom-built components also do not render in ANY AEM instance but if I pull up the local build (localhost:3000) all of the items that I did add appear.
This diagram explains that if you don't rely on existing/OOB core components/Sling Models/Sling Model Exporters and build custom components then you would need to wire each entity in a correct way either using OOB models/exporters or otherwise with custom implementations.