This question seems to have been overlooked, but the issue you have here is that the template is being opened rather than a new document created from it, so changing the following line as shown should cause the autonew macro to fire (or if you really want to open the template, add an AutoOpen macro to the template to fire when the template is opened.

Or you could add the line 
appWD.Run ("AutoNew")
to the first of the following:

Change
appWD.Documents.Open Filename:="C:\Users\Documents\Custom Office Templates\Letter 0219.dotm"
to
appWD.Documents.Add Template:="C:\Users\Documents\Custom Office Templates\Letter 0219.dotm"