$replace($1-2,$chr(40) $+ $chr(32),[,$chr(32) $+ $chr(41),])
Sorry it's a visually ugly/confusing solution. Characters ( and ) and space sometimes need to be escaped with the $chr() command in order to be used in scripts. Indeed, [ and ] sometimes need to be escaped as [[ and ]], but not in this specific case.
I will leave the rest of the script up to you, as you're dealing with Halting Default Text to replace with your own text, which quickly spirals out of control. See the help file for suggestions. If you're going to "prettyify" or alter what somebody else says, there are a million things you'll need to account for when substituting their text: Nickname prefix, Nick Colors, Highlight Colors, all the /echo flags for message/flashing/timestamp, $strip, etc, and any other preferences that affect message output appearances.