For note 347, It can be that there are multiple besieged cities next to a cloister.
In that case, only one knight can escape a besieged city per turn in total.
Note 348 aims towards cities that have multiple knights in it. Then another knight can escape in the second turn. It kinda follows 347, to elaborate that only 1 knight can escape per turn, but a builder double-turn does count as a new turn.
For the scoring, all besieged cities do not score any points at the end of the game. (Its kinda minus 1 point from normal scoring)