Thanks for joining in.
Yes, that is a fascinating point about X activating as soon as the first curtain is completely open. The light needs to begin pulsing before the instant that the opening curtain begins its travel across the film plane.
So, there is a synchronizing issue here, as you say. Perhaps lighting the tube "prematurely" at one of the "warm up" sync settings like FP might work.
I learned from fellow member Ian today that long ago the OM-4 SLR had a flash that could pulse for 40 milliseconds, accomplishing this. But I have not heard of it otherwise.
Maybe we will learn something about how to do it here.