If the $nick().pnick is only on #scripts on CID 1, there won't be an $ialchan() entry for it after you have used /scid 2.

Try this, I think it's what you're after
Code:
on *:TEXT:*:#scripts:{
  if ($cid == 1) {
    if $nick(#,$nick,~&@%+) { var %nick = $left($nick(#,$nick).pnick,1) $+ $nick }
    else %nick = $nick
    scid 2
    msg %mirror.chan MirrorScript¿ $+ $chan $+ ¿ $+ %nick $+ ¿ $+ $replace($1-,¿,?)
  }
}