I'm left handed too, but haven't ever noticed an issue on shifting bar ends, especially indexed bar ends. It's a click and that's it.
I hadn't considered dominant hand issues for bar end shifting, but if anything, at first guess I would figure right handed people would struggle, if anything, since the front is friction and has to be feathered with their off hand.
But again, this hadn't ever even entered my mind as an issue as you move the lever and it clicks into place.
Are brifters difficult with your right hand too?