on :MODE:%spyon: { msg %spy %color $+ $nick sets mode: $1- }

And that could be shortend like so

on :MODE:%spyon: msg %spy %color $+ $nick sets mode: $1-

:)

Also -

  if ($chan == %spyon) && ($1 != $null) { msg %spy %color $+ * $nick($chan,$nick).pnick ( $+ $address $+ ) has left $chan ( $+ $1- $+ ) }
  elseif ($chan == %spyon) { msg %spy %color $+ * $nick($chan,$nick).pnick ( $+ $address $+ ) has left $chan }
}

Could easily be shortend to an $iif statement, like so

  if ($chan == %spyon) msg %spy %color $+ * $nick($chan,$nick).pnick ( $+ $address $+ ) has left $chan $iif($1,With message: $chr(40) $+ $1- $+ $chr(41))