Len isn't what I would be using for that kind of a Talkloid. Anyway, the pitches are too low for the stuff to be even audible. With Talkloid, I always tend to get the best results when the words are going off faster. Try constantly fiddling with PIT and compare with how you or a normal speaker would say it. Stuff like this, practice makes perfect. Most Japanese people, when they speak, tend to speak Japanese at a very fast rate, but this also works well for English Talkloid stuff.
Also compare with my own Talkloid:
WintermintP