We have finished a game and we were defeated by the Overlord with a unusual circumstance:

The plot was one that let the OL to attack some island locations as if they were cities. Ok, so the ol had 2 lieutenants at the last location and she played a new one who appeared just there (its starting location was the island that she was besieging).

Ok, we went there to fight with the lieutenants, but the last lieutenant fled from the encounter. The rules say that the lieutenant token must appear in its starting location when he flees, right? (it cannot go to the Overlord keep because it is a land location). So the OL cannot loose siege tokens because at the beginning of the week there is a lieutenant yet, and the ol can put a siege token in his turn, too. We cannot never expel the lieutenant from that location.

Did we anything wrong? Is it correct?

The Lt. returning to his starting location is a houserule for SoB. The normal rule is to move him one trail away from the location he fled from.

(In RtL a fleeing Lt. would be placed on the OL keep, which happens to be his starting location.)

I have checked the english rules, and you are correct. Thank you. The spanish version seems to be a bad copy paste from rtl because it says clearly that "Doing so ends the encounter in a party victory, and moves the lieutenant to the Overlord’s Keep".

Super typo!!!