Yeah looking back at this, using Robot is kind of non-efficient and silly.
cylab pointed out the best way by checking for an empty input:
String s = console.readLine();
s = "default value";
Which is what i ended up using, but not what i want. I wanted the user to see the text filled in not, to have to make the mental leap (empty == filled with default). I even tried to replace System.in with a custom inputstream that had both A string at first and the normal System.in chained, but it never ended up displaying the string. It may flush it before it does a readline? Bizarre nevertheless.