Hi! I think that the first in distortion is wrong or miscalculated by blender because of too few markers on the frame borders in the motion tracking process, you can play with the k1,2,3 and the calibration grid to set a better manual distortion. Also you can calculate those “k” values in other software’s too with some photographs made with the same camera but blender does it as well.
For the antialiasing problem I think that depends from the compositor fitted preview, try launching a still render and check it instead.