Why would she need revenge? She wanted Stonn, and got him. While things didn't work the way she planned, she got what she wanted. Wanting revenge on Spock in that case would be - frankly, illogical, and more of a human, not a Vulcan reaction to events.
First - let's keep in mind that we're talking about fanfic, and this particular story was written and published ~25 years ago. Also, keep in mind the way T'Pring was portrayed in
Spock's World: greedy, selfish, bigoted, using political means to exact her revenge.
What revenge? Well, consider this: It had been ages since any woman had actually asserted her right to have two men fight to the death during a marriage ceremony. Most civilized Vulcan women who didn't want to go through with the bonding/marriage would have found another way, or just done what Queen Victoria was advised to do ("lie back and think of England").
However, in T'Pring's case, even though she ended up with Stonn, it wasn't the
way she expected it to happen, and it didn't have the long-term effect on her life that she anticipated. I'm going by Diane Duane's novel and a whole lot of fanfic here, but basically T'Pring became a social outcast after she Challenged. And Stonn wasn't pleased either, as T'Pring impugned
his honor by choosing Kirk as her champion. Yes, she had a logical reason (she didn't want Stonn dead)... but it was still a dishonorable thing to do.
There is one story that spells the situation out quite neatly: T'Pring is networking and negotiating among her female acquaintances to try to arrange marriages for her own children (hers and Stonn's). However, for some reason, nobody is eager to take her up on it. It's not because of any lack of academic credentials or artistic accomplishments or other social/clan traits that Vulcans value... it's because
T'Pring challenged. She
could have let Spock
die because she refused to do her duty. Whatever could T'Pring be influencing her
own daughter to do if she decided she didn't want the prospective husband when the Time came?
T'Pring's Challenge forever ended any chance she had of being
trusted by her peers - and her children are considered equally untrustworthy, by association.
Logical? Of course not - by human standards. But we know that there is a mean streak of hypocrisy running through Vulcan society anyway.