Auto finish the RunParallel task when the execution flows back to the target state tree's root?

I’m extending the FStateTreeRunParallelStateTreeTask because the task itself by default never finishes. The ideal behavior is to have a boolean variable for when the linked tree flows back to its root I could choose whether to finish the task.
Since the C++ ST tasks are all structs and there aren’t delegates to bind so this have to be done in tick, which is quite hard to trace…

I’ve looked into the source code briefly and there’s no easy way to retreive the current transition status from outside the tree.
The cached FStateTreeExecutionContext::NextTransition looks neat yet it’s protected; the execution state from FStateTreeExecutionContext::InstanceData seems like the perfect place to check but it just doesn’t have transitional information.
The only hackish way I’ve disocovered is to use FStateTreeExecutionContext::RecordedTransitions but it’s far from ideal as it’s recording on EnterState which is a bit too late and the container itself is ever-expanding.