There are a few problems with your code.
There’s no such thing as a “When xyzzying” rule. The rulebooks attached to actions are Instead, Before, Check, Carry out, After, and Report.
For out-of-world actions, only Check, Carry out, and Report work. So you’ll need to make your xyzzying rules one of these (or else rethink your decision to make it an out-of-world action).
“After entering Zizzy Room for the first time” won’t do anything, because “entering Zizzy Room” doesn’t correspond to any action in Inform. The player is reaching Zizzy Room via the xyzzying action, so you need a “Carry out xyzzying for the first time” rule. (Note—not “After”, since xyzzying is out-of-world.)
“Instead of doing anything other than xyzzying in Zizzy Room” will prevent the player doing anything anywhere, except xyzzying in the Zizzy room. You mean “Instead of doing anything other than xyzzying when the player is in Zizzy Room”. But Instead rules don’t affect xyzzying anyway, so this is the same as “Instead of doing anything in Zizzy Room”.
But note this will prevent the automatic look action that takes place when you move the player to Zizzy Room. So the room name never gets printed. So either except looking from the Instead rule, or else bypass the automatic look, and print the room name yourself.
The Zizzy Room doesn’t have a “printed text”, it has a “printed name”. Also, you’re changing it too late, after it’s been printed; so the new “Zizzy Room… again?” name will never get displayed. You need either to change it at an earlier stage (maybe when the player leaves the room on the previous occasion), or else deal with the change of name a different way, maybe with a text substitution.
Also, shouldn’t there be a way for the player to leave the Zizzy Room? At the moment your Instead rule will prevent that, however it’s supposed to happen.
I’m not sure I’ve understood exactly what you want, but here’s my version.
Section - xyzzy
Xyzzying is an action out of world. Understand "xyzzy" as xyzzying.
Zizzy Room is a room. The printed name of Zizzy Room is "Zizzy Room[if the player is in the Zizzy Room for the second time]... again?[end if]".
Room xyzzyed from is a room that varies.
Check xyzzying in Zizzy Room:
say "`Zizzy!', you proclaim, and remain exactly where you are." instead.
Check xyzzying when the player has been in the Zizzy room twice:
say "Nothing happens." instead.
First carry out xyzzying:
now room xyzzyed from is the location;
say "'Zizzy!', you proclaim, being instantly teleported to:[line break]";
move the player to Zizzy Room, without printing a room description;
say "[bold type][The location][roman type][line break]".
Carry out xyzzying for the first time:
say "Read this carefully, Player. This is important. I've brought you to my infamous Zizzy room to berate you by way of history lesson. You seem to know nothing about the history of text adventures, so I've done my research to properly educate you so that you can make the right choices in the near future.".
Carry out xyzzying for the second time:
now the printed name of Zizzy Room is "Zizzy Room... again";
say "Really? I thought you learned something from my words, and you decide to throw it all away by not taking my humble advice?"
Instead of doing something when the player is in Zizzy Room:
say "The room seems to fade around you, and you find yourself back in:[line break]";
move the player to the room xyzzyed from.