keyTable and update cell from external function

Hi, I'm using both FixedColumns that KeyTable.
I need to update the contents of some cells through the fields outside the table. To do this I use a simple javascript function that takes the value entered by the user and replaces it with a cell in the table.
The cells which are one inside the header (fixed), one inside the table and one in a column fixed.

The problem is that when you use the arrow keys to move around the table, the previous variation on the fixed column is lost (back to the previous value), while the others behave properly.

This is how I use keyTable and Fixedcolumns

var oFC = new FixedColumns( oTable, {
		"iLeftColumns": 1,
		"iRightColumns": 3,
		"sHeightMatch": "none",			
} );
		
var keys = new KeyTable( {
        "table": document.getElementById('tableHead'),
        "datatable": oTable,
} );

Any idea?
thanks