Tandava,
Generally, you are not supposed to change the files in the sync folder on Google Drive, as MobileSheets is supposed to manage that. The feature is intended for multiple devices to be able to synchronize their changes back and forth, but not necessarily for you to modify the sync folder to push updated files to the device. Having said that, you can enable that if you want, it's just a little slower because then MobileSheets has to scan every file in the Google Drive folder to know whether it has changed. You will see there is a checkbox on the "Sync to cloud folder" screen called "Check for updated files in cloud folders". That has to be checked if you are going to modify the files yourself.
As a side note, MobileSheets will be available on Mac fairly soon, or if you have a newer Mac with an M1 or M2 processor, you can run the iOS version on a Mac which would give you an easier way of adding annotations and such.
Mike
Generally, you are not supposed to change the files in the sync folder on Google Drive, as MobileSheets is supposed to manage that. The feature is intended for multiple devices to be able to synchronize their changes back and forth, but not necessarily for you to modify the sync folder to push updated files to the device. Having said that, you can enable that if you want, it's just a little slower because then MobileSheets has to scan every file in the Google Drive folder to know whether it has changed. You will see there is a checkbox on the "Sync to cloud folder" screen called "Check for updated files in cloud folders". That has to be checked if you are going to modify the files yourself.
As a side note, MobileSheets will be available on Mac fairly soon, or if you have a newer Mac with an M1 or M2 processor, you can run the iOS version on a Mac which would give you an easier way of adding annotations and such.
Mike