To Ke -
When a step executes, a sequence context temporarily contains a reference to a runtime copy to the step that is running. When the next step executes, the sequence context points to this next step and not the previous. The engine is basically the high level application reference so you cannot get to a runtime step or a sequence context from a reference to the engine. You must either get a ref to the sequence context or the runtime copy fo the step itself to be able to write to one of its subproperties.
Scott Richardson
https://testeract.com