A bow front curves one way. A serpentine front changes its mind - out at the ends, back through the middle, forward again at the centre - and every one of those reversals has to be carried through the whole depth of the carcass, not just applied to its face.
That is the difficulty. The top has to be shaped to the same line as the front. The doors have to leave and re-enter openings that are curving in opposite directions at their two edges. The plinth below and the apron carving along it have to follow the identical sweep, or the base looks as though it belongs to a different cabinet.
Our craftsmen build a full-size template of the front line first and work every component to that one master profile - top, doors, drawer fronts, plinth, apron. Nothing is fitted by eye against the piece beside it, because small errors accumulate along a curve and there is no straight edge anywhere to check against.
The openwork pilasters are then set at the points where the curve reverses. That is not an aesthetic choice. Those are the positions where the carcass most needs a vertical member, so the pierced carving is standing exactly where the structure wants a post.