Considering Nannerl

Last Friday was a cold, misty, windy day. But there was a glimpse of sun - morning concert in Australian National Academy of Music - ANAM and there - W.A. Mozart - Piano sonata for four hands KV381 performed by Laurence Matheson and Paavali Jumppanen.
I returned to this piece of music at home, on youtube - HERE performed by Daniel Barenboim and Lang Lang. And then a question struck me - is there any difference who plays on higher or lower keys? On the right or left side of the piano?
Many sources mention, that this sonata was to be performed by W.A. Mozart and his older sister Marie Anna in short - Nannerl. It is obvious, that females perform in higher registers, so Nannerl must have played on the right, as in this picture...

Source of the photo HERE.

I searched youtube for a performance by a mixed couple - I found one - Martha Argerich and Nelson Freire - look HERE (part  3 Allegro).
Hey - why is Ms Martha sitting on the left, in man's place? Obviously it is a sign of respect. Play Wolfgang's part. That's why D. Barenboim and probably also P. Jumppanen (overseas guest of ANAM) were seated on the left.
And what about Nannerl? Just read her biography in Wikipedia. And here - Mozart's silenced sister. Looks like still in a shadow. Who will make a RIGHT choice? Perform the right side of Mozart's sonata?