pluginInstance->setParameter (id, (float) value);

Now that VST3, AU (and AAX ?) are supporting the offsetSamples per frames, could we have an extra "offsetSamples" parameter ?

void PluginTestAudioProcessor::setParameter (int index, float newValue, int offsetSamples)

Or is there another obscure way to get this event offset somewhere else ?

I can't just change those method signatures without breaking everyone's code.. This will need to be done as part of a bigger refactoring where I introduce a new class to represent each parameter. This is on the to-do-list but is a big job!