>"how many points do I have left, guys? - Three - No, four - Three, you cheater!"
Rate of that happening seems to depend on probability of a player losing. Some games I know have a mode where no one can lose (just collect), just for that.
>Conversely, to lessen the Mermaids' super-importance slightly, I half-heartedly suggest making the Elves able to search on water hexagons that are two hexagons away.
Mermaids seem to be drastically different from others, so, maybe they could be in water pool in the center, the rest coming from kingdoms around it? Like in one game, one can find resources only in others' kingdoms, so that no one can mine their own territory?
As there are seven types total, they could be assigned territory in a big hexagon based on symmetry and their ability to fly. That way, each terrotory have practical border only with two or three others.