Wow! I loooved this report, im from Buenos Aires and i was very surprised to see this.
The majority of the rides (rocket simulator, the super 8 volante coaster, the racing cars, etc) at Lujan are from ItalPark, a parked that was in the middle of the city of Buenos Aires and closed down in 1990 after a girl died in a ride called the matterhorn.
You missed the Parque de la Costa, its the biggest park in Buenos Aires and have a few good custom coasters, like boomerang and the vekoma inverted with 5 inversions.
You should all visit Argentina, its a very beautiful and big country.
Thanks for this report!