I enjoyed the demonstration because although I could still read it I could notice that I had to spend extra effort to do so.

Exactly. I think most of us see this project as a hyperbole. Dyslexia does not make you literally see scrambled letters, but make it similarly difficult to read. I found the long and uncommon ones like "phonetical" especially difficult.

To people with dyslexia: are shorter and more common words easier to comprehend, just like in this piece?

For me the shorter words are actually harder because they are more similar to other words and they often don't attract focus in a sentence so your mind spends less time on them.

Yes. It's just my interpretation of something I heard.

Well, isn't that just burying the lede? I applaud the application of technology, but sometimes I think the neophyte approach, combined with the amplification of the web, can be more detrimental than helpful as intended.

Sorry to be uncharitable, but here is how you could've written a more honest introduction:

I heard a friend with dyslexia say that letters just jump around for her. Without asking for details, this reminded me that I had a hammer called JavaScript, and this looked like a nail to pound. So I wrote some quick code with made-up parameters and copied info from Wikipedia for cachet. I didn't bother to get any further feedback from dyslexics about this, so it is purely my folk-interpretation of a condition I don't really know about. I then uploaded it to HN to get some feedback, but I still didn't bother explaining what I did or why.

Are you on LSD?