Yes, you can update existing features using the "Import" functionality in Accompa.

To achieve this, include a column for Feature ID in the CSV file being imported, and make sure that the values in this column have the proper format of FT-N, where "N" is an integer corresponding to the Feature ID of an existing feature.

In Step-3 of Import Wizard, match this column with "Feature ID" from the 'Accompa Fields' picklist. When you click the 'Import' button - the existing features will be overwritten with values from the CSV file.