Teradata PT can retrieve values from tables containing UDT columns in the same manner as it does with other tables.
If the select-list of the SELECT statement used in the Teradata PT job contains a UDT expression, the Teradata Database automatically converts the UDT data to its external type before returning the data to Teradata PT.
As such, the data written to the output location referenced by the ".RETRIEVE" command is in the external type associated with the UDTs.