You can make layers invisible from python. Here's the syntax:
# to make it invisible
System.SetLayerVisible("Layer 2", 0)
# to make it visible
System.SetLayerVisible("Layer 2", 1)
Events that had a combo in the event sheet such as invisible|visible will be just a index number in python 0|1. All actions are implemented, just no system conditions as most of them have no context in python.