Carolyn- That’s really bizarre that the board ripped up even with the screws that reinforce the glue joint. I’ve never heard of that. I have heard of this happening in cases where the screws were left out. My only explanation is that maybe the screws are too short. They should be 5/8″ to 3/4″ long.
Re-reading your post, there is another possible explanation, and that is that perhaps the screws were countersunk too deeply so that in fact they were not able to hold the soundboard in place.