It has been a while, it seems there's still difficulty of setting up PARAMETER ARRAY in ODBC 13.10
I can't find SQL_ATTR_PARAMSET_SIZE in the ODBC trace log. The insert performance is pretty bad.
The ODBC Driver for Teradata supports Parameter Array; but I am not familiar with the DataDirect ODBC driver.
Is this a custom application or are you using Informatica? I think Informatica PowerCenter 8.6.1 does not support Parameter Array with the Teradata Database. Can you post a code snippet if you developed the application?