Hi Alex,
I can see and understand where you are coming from. However, admit my comment re the plaid at the front may be more correct for the more up to date way of wearing the plaid. Though saying that in all the photos / images you posted the plaid is hanging down the back / pulled around over the left shoulder.
Am guessing from the sporran and uniform that the figure is Napoleonic. If that is the case, the plaid will have been mostly ceremonial / cosmetic.
Have attached a couple of pictures to show you what I mean.
Kind regards,
James