JK, there are just two things that can be done to eliminate condensation: raise the temperature of the condensing surface, or lower the reletive humidity. You've done something in both these areas, but you can realisticaly only do so much; then you have to attack the source of the moisture.
The tech apparently thinks the moisture is passing throughthe brick work then in through the plaster to the interior. I find it hard to believe that this could account for as much moisture as you apprently have. It's true brick will transmit moisture, but where is that moisture comming from to begin with? In a significant number of cases, the moisture is comming from a damp basement or crawl space. Since it sounds like your climate is pretty humid all the time, I would also suspect air infiltration to be a serious contributor; the windows may or may not be involved. Actually the window itself is often not the problem, it's the way it's installed and sealed (or not sealed) to the building. Air infiltration takes place to replace heated air that finds it's way out through the attic (do you have moisture problems up there too?). Once you determine the source, it's probably possible to come up with a solution. Until then, it's just guess work.