Retrieving information about workflows via REST APID

We are trying to do a YouTrack state machine workflow visualization.

For that, we can retrieve first all workflows via:

/api/admin/workflows?$top=-1&fields=id,name,rules(id,name,readOnly,title,type),title,updated,usages(isBroken,project(id,name,shortName))&query=language:JS

The filter the rules that have type == “StateMachine” and then retrieve their definitions like:

/api/admin/workflows/$workflowId/rules/$ruleId?fields=id,name,readOnly,script,title,type&query=language:JS,system:null

and then inspect the “script” attribute of the returned objects.

However, the problem is that when the state machine inlcudeds another state machine defined in a different file, like this: 

var submachine = require('custom_workflows/submachine');

these rules are included as MiscellaneousObject and there is no obvious way (short of inspecting the script) how to find them via the REST API. Is there some attribute that can be retrieved via API that will list me all rules referenced from one rule?

Also, the official documentation on REST API for workflow information retrieval is missing (or I am not able to find it), where it is, please?