IF any custom validation available for spreadsheet cells, then while exporting the sheet, those validation error messages or formats not getting exported. So here it will be helpful if its exports validations too. So user can see error in both UI and Exported file. 
In the below example, user can see the error messages in ui but cant see on the exported file. 
https://docs.telerik.com/kendo-ui/controls/data-management/spreadsheet/how-to/validation-to-column