Even before I posted my question here, I was experimenting with layering without much luck.
With all the sliders and controls, I never did notice the one beside the Morph type drop-down box. I did adjust it all sorts of ways and still got a nasty bunch of stuttery flashing. It looked decent on the screen, but the pixel output is what looked bad, almost as though there's "frame drop" going on caused by the network connection to my controller via Bridge mode dropping frames (I'm at 25 ms timing). So, I copied the FSEQ files to the Falcon Player and when I played it, the effect was more of a fast strobe effect, and not what I'm looking for--a strobe effect
There is a mentioning of setting a value curve for the transparency to randomize the brightness intensity of the strobe effect, though. Where is that? I see a slider for the duty factor and cycle count value curves (and even doing a custom one with a jagged line) didn't seem to make much a difference, either.
In the end, I'm just leaving the concept of "vibration" and have resorted to setting "In transition" under layer blending to "from middle". Since I was constrained by the effect limitations of AC lighting in the past, I'd might as well take advantage of what individual pixel control can do.