I’d like more explanation of what you envision a left-handed violin to be? I am left handed. I play the violin, fingering with the left hand and bowing with the right hand. I actually find this to be advantageous. Being left handed, my left hand has more small muscle motion development, which seems to be required with fingering the violin. On the other hand, bowing is, in large part, a larger muscle motion and much easier to pick up learning it from the right arm. If I had to pick a mandolin or a guitar in any intricate finger pattern, it would be very difficult.
Violins, classically, are used in large groups in orchestras and ensembles, so having everyone play as described above, with the violin sitting on the left shoulder, allows for uniformity in group situations. Imagine if an equal number of players came in with violins pointing the other way. Bows and scrolls would be knocking around. It would be impossible to seat a group properly.
Why seek a ‘left-handed’ violin? The regular way of playing a violin as it is configured already provides the advantage to left handed-ness. Just curious.