I hope you are reading this, please make a feature that can cancel hundreds, thousand of all orders with just a csv import. Add a feature (if there is none) on which store has that order came from, since if the account has a lot of stores in it. We can compile it on our end (same format) then put it all in one csv file and let the magic of you developers do the canceling, it's hard to cancel 1 by 1, or reupload per store cancellation by the use of tagging, the tagging is already crowded for product type for batching/creating label purposes.
For example when we are extracting the data on your shipstation via EXPORT, the formats are the same or should be the same as importing orders for cancellation command. I know you can do that. Shipstation is supposed to be like that since others are experiencing this kind of problem too if they are shipping hundreds or thousands of orders.