@Pieter Boelen, I just made the tests you asked and the results where the following:
- Charlestown at day: After fighting all waves of reinforcements and the soldier standing in front of a building, I guess it is a naval academy or something like that, the dock was locked (couln't get back to my ship), as was every other building in town. Interestingly, I could speak with the street vendor and bought more bandages. The guards killed every armed person in the streets, probably bandits, only one unarmed citizen remained and he didn't run from me in fear, I could speak with him normally.
- Port Royale: Both at day and at night (in transformed shape) I could get back to my ship, even with guards chasing me. As expected, the citizens and vendors didn't talk to me in fear. Rys Bloom attacked me, I killed him and the other day when I came back, he was substituted by Brendan Legh, wich had the same dialogues and probably could get hired in the same way.
I've taken more screenshots, but some of them had more than 2MB, including the one showing Charlestown at day. In this one, instead of the ship icon there's a lock icon.
PS: Just noticed one thing, in Charlestown, the icon spells "Sea", while in Port Royale it's "Ship". By the results, the problem must be with non-vanilla cities, and probably has nothing to do with the Curse.
Lucky cap'n sounding more like cap'n obvious eh? Arrr!