The mighty little CV 1.7/35 is actually more flare resistant than either the ZM 1.4/35 or Loxia 2/35 so flare resistance is not a general issue of CV lenses.
And with the CV65 it is far from bad either, the Lox50 for example does not perform any better. It is just that it beats the high end competition in almost any aspect but some lenses outperform it's flare resistance.
The mighty little CV 1.7/35 is actually more flare resistant than either the ZM 1.4/35 or Loxia 2/35 so flare resistance is not a general issue of CV lenses.