You cant' replace w with s in this case, because when doing $read(test.txt,s,$nick) the script will read from the text file, and scan for that word ($nick) and it will return what is following that first word on the line.
Example (here I go again giving you a scripting tutorial, because you obviously need one):
In your text file:
fiberoptics this is the text that will be returned
//echo -a Result: $read(test.txt,s,tsoglanos)
--> Returns: Result:
//echo -a Result: $read(test.txt,s,fiberoptics)
--> Returns: Result: this is the text that will be returned
In other words, your %m will always be empty even if it did find a match in the text file, because in The_Game's text file it is only nicknames, with nothing following it.