In ExampleScenario, between instance, process, and actor the resource appears to be building an internal graph using key properties and string-holding "reference" elements (see also FHIR-43903).

I am worried about using FHIR elements this way. Elements, including backbone elements, already have an id property. Similarly, there are ways of having "contained" resources and "references" - using words like "contained" and "reference" with different expectations than usual causes implementer confusion.