I am left handed and prefer to shoot left handed guns like the one in my avatar. However, I do have a few RH flintlocks. The glasses I am wearing now are pockmarked from shooting my right handed Steve Krolick Cossack rifle portside. I would not consider shooting a RH flint or caplock from the left side without glasses.
You should always wear eye protection on the range whether you're shooting or not, due to the possibility of backsplash. There's also a pockmark on my right lens from someone shooting a modern pistol at steel plates from 25 yards.