You said bone transform, but only seem to care about translation. A little pedantic, but the transform consists of translation, rotation, scale, and shear. Also a bone has both a local and a world transform.
Other things can affect bone transform besides a translate timeline, such as translate X/Y timelines or constraints.
If you want the bone's local transform and don't care about constraints, you could find the translate, translateX, and/or translateY timelines and apply it. The easier thing to do would be to pose the whole skeleton for a particular frame using Animation apply, then access the bone local transform (eg Bone x).
If you want the bone world transform OR you want the bone local transform and care about constraints, you'd need to call Animation apply then Skeleton updateWorldTransform, then access the bone's world transform (eg Bone worldX) or applied local transform (eg Bone aX).
