How to deal with hierarchical data with Reflux stores?
Yes, it is perfectly reasonable to call actions from a store. I see actions as initiators of data flows and I consider exceptional flows as seperate ones.
A good example is a CRUD store that also handles AJAX calls (to CRUD the data with server-side). The store will trigger the change event as soon as it's data gets updated. However in the event that an AJAX call fails, it should instead start a data flow for that instead so that other stores and components can listen in on those. From the top of my head such errors are in the interest of a toast/notification component and Analytics error logging such as GA Exceptions.
The AJAX example may also be implemented through the preEmit hook in the actions and there are several examples among the github issues discussion on that. There is even this "async actions" helper.
It's by design that the stores only emit a change event. If you want to emit other kinds of events, it basically means you're starting new data flows for which you should be using actions instead.