Hi, can you tell me the name of the town/castle?
I'm sorry, I really can't remember, its been quite some time back now, but it happened twice in a row, so I really don't think its something that rare and a lot of other players might have gotten the same issue if you ask around.
And I believe it happened a lot more and maybe even with other factions, as sometimes a battle would take forever to end with only 1 or 2 last enemy soldiers alive and when I went to check, all my soldiers were around a house or a wall or something and then it suddenly would end which means someone might have had a lucky hit and killed them when they were stuck somewhere barely reachable.
These two were the ones my soldiers had NO WAY of reaching or hitting and were stuck for a looooong time.
Maybe something like League of Legends fix could work here?
LoL had a similar issue at the beginning where if someone used "flash" summoner spell and got stuck inside a wall, they would fall out of the map, so the added a fix where, if any body is inside of a wall, they will be pushed and "pop" instantly outside of the closest wall, which created the mechanic where you only need to flash or your skill only needs to move you up to more than half of a wall for you to cross the whole wall.
In bannerlord's case, such a mechanic would ensure something like this would not happen.
If an NPC or even the player were to fall through the floor in a way they would get stuck like that, they would instead be pushed out and "pop" out most probably where they were before falling in, as that would invariably be the closest spot outside of the wall or floor.