The synced record Task has a self-referential relationship defined in the column parentTaskId.

Use a!queryRecordType() With a filter on the task id, with fields specified to return recordType!Task.name and recordType!Task.parentTask.name.

Create a sync-time custom record field on the Task record called parentName. Specify this field to return in the query field selection.

Use a!queryRecordType() filtered on the task id once to return the task name and parent task ID. Query the record again to return the parent task name.