Looks interesting! A few things to note about this:

Those v-shaped ticks are super confusing - I might go so far as to say objectively wrong for the labeled axes, since only one of those directions corresponds to the labels. The ones on the left axis should be horizontal, because lines of constant C are horizontal. And the ones on the bottom axis should be tilted northeast to match lines of constant CR.
The right axis could stay as is, with v-shaped ticks and no labels, just to mark the other end of the lines started by the ticks on the other two axes.
But that means this version has no way to show all three components; the third one is just "whatever's left" and the right axis is the line of the third component absent. I'm guessing for the use case you're showing the third component is just a solvent/filler ie something you don't care about per se, and that's probably a pretty common use case. We may want to use that fact as the way to enable this mode. Something like:

ternary.tickorigin = ('a'|'b'|'c'|'')

to say "start the ticks from pure B" etc - which would prevent showing ticks for B itself.

In principle there's also a configuration where all three axes are flipped. Right now we have the increasing direction of all axes' labels going clockwise but it would be possible to have them all counterclockwise. That would have to be either a separate attribute (ternary.tickdirection: ('clockwise'|'counterclockwise'?) that's only valid if you don't use tickorigin, or perhaps we can find an attribute name that would make sense with values like ('a'|'b'|'c'|'clockwise'|'counterclockwise'.

Add way to reverse ternary axes #4010

Description