The question of magnetism is not much meaningful in this case : even if CuNiFe is magnetically weaker than other materials, rod magnets typically exhibit a stronger surface magnetism than any steel pole conveying the magnetism of a bar mag under the coils.
What rod magnets change, that said, is the measured
inductance: a same coil hosting magnetic rods is less inductive than if it hosts steel poles, especially if these steel poles go through a keeper bar (reason: the more iron there is, the higher is the measured inductance).
Rod mags also imply a higher Q factor.
Anyway: I've a CuNiFe in neck position of a "Magnificent Seven" ltd ed Fender Telecaster.
It measures 10.34k and 4.8H of inductance, not far from a P.A.F. clone measuring 8k to 8.5k.
IOW, the added wire seems to be there to boost the inductance, itself translated by a stronger output level, regardless of the magnetic strenght involved (which doesn't mean that magnetism is indifferent, of course: I'm just saying that more wire appears as a way to compensate the missing inductance in this case, rather than a remedy to some magnetic weakness which is factually not a real problem in itself).
FWIW: two geeky cents, just for the pleasure to share.
EDIT - I've modified my CuNiFe to make it splittable. In single coil mode, it measures 5.25k and an inductance of 2.1H, just like a Strat PU.
It doesn't sound strong in single coil mode but it's a
really musical transducer to my ears... No regrets!
The only downside is that I had to pull off and put back the CuNiFe screw poles upside down: the pickup was OOP with the stock Tele bridge PU and/or the split mode was not involving the right coil otherwise.