If an assassination is successful, can the infiltrator still be caught?
Yes. There are many opportunities to fail when assaulting someone.
Kind of tangential (as it's a mechanical question), but could for instance Duke Kepler be stabbed by Sir Evil, who is caught in the act by, but escapes (or doesn't), the guards?
If by "caught in the act" you mean "spotted and identified, but not physically captured", then yes. You can perform a flawless assassination, but get clearly spotted and identified, but still escape unharmed and uncaptured.
I do really like the idea of making character deaths more flavorful. "Character died" just seems really drab when it could be "Character executed by order of the Judge of Keplerstan". Speaking of which, how difficult would it be to add a check to see whether the cause (judge's name in case of execution, or character for hero's killed in battle) is known and include that in family history? Or is that basically the job of players and what the Wiki is there for?
The executing judge's name is already recorded in family history. Death in battle probably could be done without too much difficulty, as the unit responsible is already reported during the battle.
