What is the position of my keyframe animated object?

I'm an experienced developer but completely inexperienced with 3d modeling and python.

I have a modeled a Rubik's cube containing 26 (center omitted) cubes where the center cube, if I had one, would be at 0,0,0. When I rotate a face with keyframe animation, all of those 6 cubes report a location of 0,0,0. I think that is because it is reporting their pivot which I have set to the 3d cursor at 0,0,0.

somecube.matrix_local appears to be interesting but the documentation does not say what the return values actually represent and I cannot see the pattern I would expect on the results of adjacent cubes.

All I want to know is how I can find cubes by name on a certain "face" of the Rubik's cube. So all cubes on x = 0 or all cubes on x = 1 or all cubes on x = -1 and likewise for y and z. Or more generally, how do I get the center coordinates of an object that has been animated by keyframes?

If the object has not been animated, the location is obvious but I'm lost once I rotate anything around 0,0,0 which is where I set the 3d cursor.

for reference, cubes (each size of 2) that I would expect to be at (2,2,2) , (2,0,2) and (2,-2,2) show:

>>> ob1.matrix_local
Matrix(((1.0, 0.0, 0.0, 0.0),
        (0.0, 1.0, 0.0, 0.0),
        (0.0, 0.0, 1.0, 0.0),
        (0.0, 0.0, 0.0, 1.0)))

>>> ob7.matrix_local
Matrix(((1.0, 0.0, 0.0, 2.0),
        (0.0, 1.0, 0.0, -2.000000238418579),
        (0.0, 0.0, 1.0, 1.999999761581421),
        (0.0, 0.0, 0.0, 1.0)))

>>> ob4.matrix_local
Matrix(((1.0, 0.0, 0.0, 0.0),
        (0.0, 1.0, 0.0, 0.0),
        (0.0, 0.0, 1.0, 0.0),
        (0.0, 0.0, 0.0, 1.0)))