Wrong service. Since RS’s imitate Vera-standard security sensors (which define and maintain Tripped), you need to use Vera’s standard service ID. Try this:
local lul_Windy = luup.variable_get("urn:micasaverde-com:serviceId:SecuritySensor1", "Tripped", 152)
By the way, you can see the service ID associated with any state defined variable on the device’s Advanced > Variables tab–just hover over the state variable name, and a tooltip will display with the service ID.