We transplanted a number of box bushes, and although all looked good for several months, some then slowly went dry, brown/yellow and died. Probably did not water enough (we're plant and forget types sadly) but my point is that it took ages and although they seemed to have taken they clearly had not.
Maybe you could quickly take some cuttings so if they do turn up their toes all is not lost.
On a slightly different point has anyone taken successfully taken cuttings from Box bushes? We have read up all we can find, but they only say "overwinter" in pots. But does that mean in the house, outside or what? ie how sensitive are they?
We have, however, learnt that they don't like being water logged in winter, but that is only a problem if they survive until the winter...