From other feedback I understand that it's hard for you to upgrade the reports with exclusion of subtasks functionality.
From the API's point of view you have the property superTaskIds at hand.
Is it possible to include that field at least in the reports?
If the field is null (its a task) if that is poulated it's a subtask.
So a sort of calculated property should be quite easy to develop.
IsSubtask based on null/not null on the value of superTaskIds
Please investigate if this could be done. It seems like a low hanging fruit that would be most helpful to sort/filter the reports from this data.