While the editor may not support custom frame-limited playback,
the runtime can be set so that it updates the skeleton in large discrete frame intervals, which would achieve the frame-limited/stop motion look.
What needs to be done is change out the logic of whatever is updating Spine.AnimationState. Only pass it specific amounts of time in the code, and only when a certain amount of time has elapsed (ie, the target framerate).
Doing the frame-limiting at the skeleton level at runtime (versus the "baking" you describe) is more ideal since all those extra keys add up to more memory usage, is slower to load and slower to process at runtime and, being "baking", makes the animations unworkable.
