In most cases if the chained cut in box are not properly aligned to the next one and held secured it can add up to what you see.
The installer did one or two things wrong; they didn't secure the boxes properly together, and they didn't watch the alignment of the devices they installed.
If the box where all correct. You could have tryed to correct this little bite of the spacing on the devices by pushing the last two to the right, then add and test each cover plate.
There's no way to easily fix a striped box connection screw, which can be caused easily with popeye arms, or the ever present usage of power drills. I guess you could use neddle noses and try to adjust them, but most if not all the devices would have to be removed.
You'd probably have to swap the last two devices on left you have to any chance of finding a
matching 4-device cover. Finding a 3 switch with a GFCI size blank one would probably have better odds.
I also inverse the cover plate to check spacing and bubble check before I use cover screws.