For any error with customer deposits you should first make sure you have correctly configured your customer deposits by following this article:
INSUFFICIENT_PERMISSION - You do not have permissions to set a value for element undepfunds due to one of the following reasons: 1) The field is read-only; 2) An associated feature is disabled; 3) The field is available either when a record is created or updated, but not in both cases.
Usually this error indicates that you may not have the "Account" field set to show on your Sales Order form and therefore FarApp doesn't have the permission to write the customer deposits into the required fields. Please check the NetSuite Sales Order form FarApp is using and make sure that the "Account" field is visible (i.e. the "Show" box is checked in NetSuite). Note that by default FarApp uses your Preferred Sales Order form.