Ask SF support - they can review the backend error logs, but it might be a lot data for them to sift through.
I have heard about errors like this and at times it was due to CPU overload of the connected SF org, for example:
System.Exception: message = "TaskTrigger: System.LimitException: Apex CPU time limit exceeded", statusCode = "CANNOT_INSERT_UPDATE_ACTIVATE_ENTITY"
If this would be the case, try adding wait steps and random splits before the Task creation activity - this should attempt to create Tasks in smaller batches reducing the CPU load.