I’m sorry to hear that you didn’t get quite what you wanted, but you are correct, the initial assumption was mistaken. Elinchrom’s A-series of heads are for action and have a shorter flash duration. They freeze action, like sports, but producing an extremely short pulse of light, but that doesn’t change your cameras sync speed.

To simplify the process, think about it as shutter opens, light flashes, shutter closes. If you shorten your shutter beyond the maximum sync speed, then the shutter will become a slit that travels across the film plane instead of fully open. When the flash does fire, the shutter will be blocking part of the film plane. To really see this in effect, try a shot with the shutter at 1/500th of a second. You will see just how small the moving slit really is.

Unfortunately, there is no way to change the maximum sync speed of the camera. But you can adjust the aperture, ISO or even add a neutral density filter. The other choice is to switch cameras. You could use a camera with an electronic shutter (i.e. Canon G10) or a leaf shutter (Hasselblad, some Mamiya and others).

Hope this helps.