First of all, there are several bugs in the script! Try to open it with the editor in debug mode, and you'll find a host of problems. Did you never wonder why your natives are not being placed?
The basic map design looks fine, but the many empty cliffs look just plain ugly.
The limited coin makes for a big balance problem. Since players don't even get a starting mine it's possible that the only source of coin in one's half of the map (apart from trade posts) is the factory. That will leave a player hopelessly behind an opponent who can rely on mines in addition to the factory.
The starting factory was an original idea, but I don't think I liked it. The problem is that the games I played simply turned into a cannon war. Field a heavy cannon (less than two minutes into the game), then advance and kill either the opponent's cannon, factory or town center. Stopping a Spanish player, who's able to field war dogs in discovery to support his cannon seems almost impossible. Maybe you should use triggers to disable cannon production until Age IV in order to solve this problem.
As for the "at least 2 hours against the computer" you promised: The AI has no idea how to use the cannon in the early game, so a human player can simply attack the AI with the cannon and win easily in about three or four minutes, even on expert.