I don't see what the improvement is, in mine there are those corner cutouts, and everything is constrained. The measurements also don't fit this diagram.
the cut outs in the corner are not present in all pictures of the rails, also those dimensions are rounded to the second decimal and if you construct the sketch by those measurements the total measurements dont add up. for instance the measurement sown in red here. the diagram you linked says it should be 1.5mm however that is a geometric impossibility when you apply all the constraints. what your linked diagram does not show is the distance between the the closest or farthest points in the slot. I went and searched for that measurement and it is 6.773 mm.
