Reversing vertex duck order

First off, I applaud the sheer amount of effort poured into this project. I am constantly impressed at the breadth of tools available in Synfig while still being relevant (in fact, while writing this, I found about half a dozen more tools I was previously unaware of).

Attached are three gif files of a wagging tail to illustrate my problem (I made it asymmetrical to prove my point).

Ignoring the fact the tail would extend out when wagging, the plan is simple: make the tail wag from one side to the other and back again using the Mirror Tool (similar to Tail Manual). It looks like I have all keyframes in order as Tail Keyframes shows, but when I render, the tail simply rotates on the y-axis as shown in Tail Rotate. I’m not too surprised at this behavior and should not have expected any less as geometrical reflections simply work in this manner. The reason being is that the vertex ducks are now in reverse order. I was wondering if there was a solution to this as I have found none so far.

I realize no amount of software will eliminate the necessity for hard work and proper keyframes. I also realize that with some shenanigans, it would be relatively easy with similar scenarios to move the offending ducks (be it manually or by a convoluted series of reflections). However, not all B-Lines will be as clean-cut or simple.

tl;dr How do I reverse the order of the ducks after reflecting them?
Tail Rotate.gif
Tail Keyframes.gif
Tail Manual.gif

Not possible by now. The only way to do what you want to do is doing it manually as your third example.