the setIntensity is set as a method on the object and not as a ScriptParameter.
that would be sth. like:
LFOModulator.setIntensity(value); instead of LFOModulator.setAttribute(..., ...)
Also FX won't work, as there is no Intensity there. The setIntensity() method mainly works with the Modulation Processors (VoiceStart, Envelopes, TimeVariant) on the Gain and Pitch Tabs.
ahh you found out yourself.. 😉