Hi Tim,
NVQ is recognised in NZ, but only as far as immigration. You'll probably find employers will accept that she has this qualification, but will not utilise it in its NVQ form.

I expect it will boil down to what job your wife takes on. If it is dependant on being qualified, then she might have difficulties.

It might be worth contacting the NZQA to see whether they can give her some kind of translated qualification, or whether she will need to retrain.

Hope that helps