Can you update more than 1 field with SSJS Rows.Update?
SFMC Documentation Update(object, filtercolumns, filtervalues)
This function updates the specified row with the specified information.
Arguments:
* object - Contains the name of the column to be updated and the value to which to update it
* filtercolumns - Identifies the columns in which to search for data
* filtervalues - Identifies the values to be used in the search
object references column...singular.