Nate wroteNice GIFs, shows your problem clearly. 🙂 FWIW, GIF quality tends to be a lot better if you make the Spine background a solid color.
You can use a transform constraint to place a bone as if it were the child of another bone. This allows you to give the "child" bone the rotation and translation of another bone (the "parent"), but not give it the scale (set scale mix to 0).
Some runtimes do allow you to scale the skeleton's container (often a scene graph node, depending on the n game toolkit) to scale the whole skeleton, rather than scaling the root bone.
Hell yes, worked perfectly.
In case anyone reading this also needs to know, here is how it's done:
1) move forearm bone to be a child of root (instead of upper arm)
2) with forearm bone selected, new -> transform constraint
3) set the target to the upper arm
4) select the transform constraint and (with the arm still in its original position) press the "Match" button, which will set the rotation/translation offset between the upper arm and the forearm to what it is currently
5) under "Mix" set the translation and rotation slider to 100
Thanks Nate, and thanks for the GIF tip too 8)
Edit: Hmm, looks like by setting the translation and rotation mix to 100, you then can't adjust either of them during animations (was expecting to be able to adjust the "offset" on the transform constraint, but it didn't allow me to).
I think I will set the "rotation" constraint back to 0, and manually rotate it (and keep only the translation constraint).
Unless I'm missing something and should be able to adjust the forearm even if the constraints are set to 100?