I've figured out that if you undo the entire buffer of keystrokes that Word saves and then repeatedly hit redo you can recreate what he's been typing. I have no idea how long this took him or how much additional work was lost as the buffer hit it's limit. Here's a video of me playing back his typing.
There are only a few hints that I can give to help understand. I'm pretty sure tooch and tootch are his idea of the sound a train makes. He has a talking train (Toots) that goes to the station among other places. He's been watching PBS kid shows on You Tube lately, including Timothy Goes to School.
I'm nearly certain that he has never seen transcriptions of any of this and so his capability for audio capture coupled with his spelling skills lets him type this. His verbal capability for original thoughts (i.e. non-echolallic speech) is very simple sentences and more likely single words and always very concrete concepts - no feelings or the like.
He always fascinates me.