Only components on specialized ParallelGroups would solve on different threads. A Reduce component would “isolate” data from outside the ParallelGroup and yield data from the group only in a single threaded manner (same trhead as the rest of the definition). Which is the whole point with single threaded “orchestration”. A proven concept avoiding just the typical problems you mention. (old components essentially unchanged, since the orchestration mechanism deals with the concurrency issues).
// Rolf