Put simply, if a player doesn't want your character to know something about theirs, then you should respect their wishes since they're the book-keeper for their characters. Time travel is a particularly hard thing to adjudicate in FFRP because it's assuming a lot of things (like Jit having access to Council records in his past when no one who controls a Council player has okay'd this) instead of roleplaying them out.

It can work in a setting with a lot of OOC agreements over what you can get away with, but if people aren't agreeing, then we should probably step back a bit and adjust how things have gone.

That being said, the Council is public knowledge, so him finding things out is probably not too much of a stretch, but assuming he can find out in backstory without checking first is a bit off in my opinion.