Indeed they ARE the ones on the fortress. Without your additional "put-the-fort-there" code, they're floating in mid-air. 
Funny, but with the code as-is, people might encounter that outside the quest, which we probably don't want.
I'm removing the "Muelle_shore_03" Build_at code for the time being;
you can put those lines in your storyline's init files somewhere, same place as you're adding the fortress itself.
Edit: Never mind, I'm beign stupid again. It's a quest-only location that nobody is going to see outside the story.
In fact, why don't you permanently add the fort through the same INI file like this?

Funny, but with the code as-is, people might encounter that outside the quest, which we probably don't want.
I'm removing the "Muelle_shore_03" Build_at code for the time being;
you can put those lines in your storyline's init files somewhere, same place as you're adding the fortress itself.
Edit: Never mind, I'm beign stupid again. It's a quest-only location that nobody is going to see outside the story.
In fact, why don't you permanently add the fort through the same INI file like this?
Code:
//Always
Locations[n].models.always.locators = "Shore06_l_xb";
Locations[n].models.always.shore = "Shore06";
Locations[n].models.always.shore.foam = "1";
Locations[n].models.always.seabed = "Shore06_sb";
Locations[n].models.always.seabed.foam = "1";
//Locations[n].models.always.grassPatch = "Shore06_g";
//Adding the fort right here:
Locations[n].models.always.fort = "fortaleza";
Locations[n].models.always.fort.locator.group = "goto";
Locations[n].models.always.fort.locator.name = "locator4";