Difference between CDA and ILS at Mimimums
On an ILS with the glideslope flown within tolerances, descent past DH is within terrain margins, indeed, all the way to TDZ.
On a CDA with substantial headwind, the aircraft can drift back into a zone where terrain clearance margins are not defined. But in this case, the aircraft ended below the runway. There may well have been an influence from the quite considerable downslope wind, but this is not addressed by TSB.
In the tailwind CDA case the aircraft is blown towards the threshold and airspace with designed in terrain margins.