I'll give you credit where credit is due. Those few pictures you posted were successful voilated NA bows. But you can't know how many broke to get those succesful ones, nor their intended draw length. You also can't say that all NA bows were unbacked voilated bows. I could pull up just as many unvoilated native american bows if i searched the web, as well as backed ones. Cherry picking photos just isn't going to cut it. It's a start but you need more man.
If you really want to prove your point just link the sientific article, or post a picture of one of your bows its that easy.