This should work and you can do it more efficiently with $istok
Code:
on *:TEXT:*:#mychan: { 
  if (!%flood) {
    set -u5 %flood On
    if ($istok(example1 example2,$nick,32)) {
      if ($istok(example3 example4 example5,$1,32)) {
        msg $chan $read(example1.txt)
      }
      elseif ($istok(example6 example7 example8,$1,32)) {
        msg $chan $read(example2.txt)
      }
    }
  }
}