I can find the relationship between an EXEC VARA and the executable object it calls, but only in the object tables, and only from VARA-to-object, not the other way around. So far, I have not found anything useful in the tables associated with active tasks.
I inserted a :WAIT 3600 command into the executable object called by an EXEC VARA. I then clicked the Preview button to trigger the task, and did some digging in the DB to see if I could find out where the relationship between the called task and the EXEC VARA might be stored.
The only thing in the EH row that I cannot identify is EH_QuAcv. I thought it might be a reference to something in ACV, but I wasn't able to find anything.