I hope it works out with the JLC date wheel alignment. From your photos, it looks like the standard ETA date wheel is reasonably well-aligned in the radial direction, but off in terms of the angular alignment. This would suggest to me that any date wheel designed for a date window at 3 o'clock would have the same alignment issues with the gen dial.
Given that Vacheron doesn't use the standard JLC date wheel, it's certainly possible that they created a date wheel for precisely that strange date window location asymmetrical about the 4 and 5 o'clock markers. Who knows, I hope I'm wrong, and that it works out.