The countEnemy command doesn't appear to work as one would expect. Search the forums for "countEnemy" and try the appended test mission.
My impression of the the countEnemy command is that it works much like Detected by ..., but its output is the number of enemies who consider the unit a threat to be engaged.
In the test mission, you have two radio commands: Alpha (0-0-1) will output the countEnemy of the trigger area, and Bravo (0-0-2) will list the units in the trigger area. The countEnemy number will not rise until the enemies have turned round and spotted you as a target.
Possible uses of countEnemy
You could use it for the final possibility in your attack on Lamentin, as it should give a positive number output once "the Enemy has spotted West", but you may find it easier to use knowsAbout.
It could also be used in place of a "detected by" trigger for an alarm when infiltrating as a lone-wolf, but I'm not certain it has any advantage.