This request does not make sense to me. Consider an example like yours, but with the labels of A, B, and C for the components.
The very top vertex is A=0, B=1, and C=0. If I could reverse the B axis, the top would now be A=?, B=0, C=?. What should A and C? They can't be zero anymore as A and C will need to add to 1. There are an infinite number of combinations. So, you want to show all of them, right? Well, that will be the very bottom of the graph where B is already at 0.
Ultimately, the ternary graph takes into account that the components add to 1. Reversing the axes would break that constraint.
Please explain further on what you are trying to do, as I feel that I am missing something.
Dan Obermiller