Currently, there is a KB that demonstrates how only values can be pasted into the Spreadsheet. However, to achieve pasting values the cells are modified programmatically, which leads to an improper undoRedo stack. In the knowledge base article if the user presses 'Undo' then a single cell will be undone. 

We can add the editing of the cell using commands as demonstrated below, but this will require the user to undo the changes cell by cell and not the entire range at once:

spread._workbook.execute({ command: "EditCommand", options: { value: value, operatingRange: range, editRange: range}});

I think that it will be a good improvement if the Spreadsheet can be configured or if it provides a method that will allow paste-only values that will be properly added to the undoRedo stack and without additional customizations. 

Regards