If it does not work for you, try to be more specific than \'it doesn\'t work\'.
Without information regarding how you configured and tested it, I can do little to help you.

Nevertheless, I noticed a bug:
:NICK | if ($newnick ison $2) { goto nexti } | var %com = msg $2 $+([,%net,]) $nick is now known as $newnick | goto output

should be:

:NICK | if ($newnick ison $2) { inc %i | continue } | var %com = msg $2 $+([,%net,]) $nick is now known as $newnick | goto output

An earlier version of this jumped to a label instead of immediately continuing the loop like it does now, and this occurence of the goto was forgotten.
It\'s not related to your problem however, since it would just spit out an error in case of a nickchange combined with a relay output channel on the same network as the nickchange where the nick is als present, this to avoid seeing a nickchange AND a message from the script (=double reporting).