i tested it in a LAN game against myself, and it's still there. the first few bombs look like they're absorbed by the shield, but then the last ones get through. i think it's because the bombers fly through the shield, since they fly so low, and the shield gets pretty high at its apex. even units at the very edge of the shield still get destroyed
that XML tweak would probably do the trick, since if they have to start the bombing run from farther away, it's unlikely any of the ending bombs would be launched while the bombers are inside the shield. unfortunately i don't think that will fix it for anything but single player, or LAN games where both players have the tweak.