Yeah, I got you. I'm saying I get the event for imprisoned children as well.

When I go raiding I usually have tons of rivals after some children have grown up, and as long as I educate them to be pagan as well I can even fight the female rivals without penalty.
(If both parties are pagan it's one of the exceptions to the penalty for fighting females as a male.)
In my current game I haven't been raiding in ages since I got locked up in seclusion for YEARS due to the black plague.

My total prisoner count went from over 100 down to 5. Yet I still have 12 rivals, all of them from giving them Ambitious after they hit adolescence. One of those is a son of mine, the other 11 are former prisoners.
I don't know why you don't get the event, though. Maybe it will only pop them for children that are covered by the Conclave Childhood Focus Alerts game rule setting? I dunno, it's weird that you don't get them and I get them for virtually every imprisoned child.
EDIT: Ok, I think I may have located the issue. For the ambitious/rival event (ZE.13615) to fire the children have to be in house arrest, not the dungeon or the oubliette. I usually put children in house arrest as soon as I capture them, so that's probably why I got so many rivals from them.
If you wanna verify for yourself it's events\ze_adolescence_events.txt lines 5206-5211 (I have not updated to the latest update, so line numbers may or may not be slightly off).
I have the same issue. It's annoying as heck that there is no notification when the Court Tutor dies. The way I get around it is by starring him as a person of interest and setting the message setting for deaths for POIs to a pause and popup.
The only issue then is remembering that it was the Court Tutor when it pops, heh. But it's not too hard because I almost always use monks for their society boosts, and you can tell by their tonsure.