Lately, I've been learning more about Transform Constraints, but I've experienced a limitation that affects my convenience animating and wonder why it hasn't been addressed soon.

I am trying to set up a facial rig with an almost complete 3D-like mesh animation, with individual parts (eyes, mouth, hair strands, etc.) parented to their own bones that share a single Transform Constraint and have their own Mix value. Each facial parts need to have a differing ratio of Transform and Scale mix, because most of the faces I create won't be symmetrical or facing directly in front. When I had a bone target two constraints as an attempt to use these constraints to handle horizontal and vertical adjustments individually, adjusting the Mix on the two constraint bones actually divides the Mix and apparently messes up the ratio.

So, I was wondering if there is any way Spine can update the Transform Constraints feature to let us adjust the horizontal and vertical Mix (for Translate and Scale). This would be an immense convenience for facial rigs that have varying widths and starting angles. And Offsets cannot be used in Animate mode.