this is fun to watch...
I like the french accent too...
I think the alteration of the boxes didn't require going down to only 3. I think 5 would still work, if the were uniform. Also, the columns should be the same width, but the heights only require matching in pairs.
Extra space is ok too... they might wish to add an item later, so I always leave enough space for at least one item in each box.
Remind them that the menu sign will probably last longer then their prices and products will remain unchanged.
Each of the 5 sections could be easily updated by covering that section with an update, (or if cut vinyl, sometimes by removing some lettering)
Where you have drink size info, maybe make a sub-column with size info, instead of repeating that info.
On your upper left box, this could help keep the box more narrow, and make it taller instead, to allow for the column headings. This would also make it more similar in size to the box next to it.