I would love this. I haven't bought any personalities yet because none of them suit my characters (and all the animations seem weirdly over-acted) but if this one was available I'd definitely buy it.
One of my characters sort-of is left handed because she dual wields and I always put the sword in her left hand and the dagger in the right. That's following on from Skyrim where I did it by accident - I was playing on the Xbox and you pressed the bumper buttons to equip weapons, because I'm left-handed in real life I'd always push the left one first so her main weapon always went into her left hand.
I suspect it might be surprisingly hard to do though. The simplest way would be to mirror image the entire character but that might cause weird issues. The only game I've heard of that did something like this was Twilight Princess - in the Gamecube version Link is left-handed, in the Wii version he's right-handed and supposedly it was easier for them to flip the entire game than to change the character. I'm not completely sure that's the reason but it definitely is true that the Wii version is a mirror image of the Gamecube version.