In that thread, the fellas with the Pony Preservation Project were analyzing leaked assets to see how they tick + try to convert them to 2D rigs for use in Blender.
Clipper Anon posted this specific turnaround of Trixie.
It was pointed out in an earlier thread that the leaked puppets were intended for a heavily modified version of Flash 8. This predictably caused issues with the conversion process. As shown in a video posted in a previous thread, when you extend the duration of a leaked scene, you’ll see the different rotation angles for each pony - placed at the end of the sequence, instead of being implemented via symbol swaps.
I suppose we now know why they used Flash 8 for the whole series. Editing the mods and scripts to work with a newer version of Flash would be a massive undertaking.