on ur ban line how about setting a banmask to it cuz they can just change nicks so maybe
for ircd

ban -k $chan $nick 2

for Chatspace

ban -k $chan $nick 4

i dont see why you add a var for the channel and then write it to a txt file.. just add the channel to a var then use tokens to check the channel maybe like this

alias badwchan { 
  if (!$istok(%badwchan,$1,44)) {
    echo -a Channel: $1 is now on channel protection list!
    set %badwchan $addtok(%badwchan,$1,44)
  }
  else { echo -a That channel is already on the list! }
}

and then use this line to check for the channel on ur on text

if ($istok(%badwchan,$chan,44) && %badw == on) {

another thing is that it warns/kick/ban\'s for wildcard matches like say i add hell for a bad word it triggered on hello =/

[12:20 am] hello
[12:20 am] -sick0- First warning, do not say that badword again.
[12:20 am] hello
[12:20 am] -sick0- Warned you the first time, this is your last. Next time will be a kickban/akick.
=/