  Magnetic impurities with sufficient anisotropy could account for the observed
strong deviation of the edge conductance of 2D topological insulators from the
anticipated quantized value. In this work we consider such a helical edge
coupled to dilute impurities with an arbitrary spin $S$ and a general form of
the exchange matrix. We calculate the backscattering current noise at finite
frequencies as a function of the temperature and applied voltage bias. We find
that in addition to the Lorentzian resonance at zero frequency, the
backscattering current noise features Fano-type resonances at non-zero
frequencies. The widths of the resonances are controlled by the spectrum of
corresponding Korringa rates. At a fixed frequency the backscattering current
noise has non-monotonic behaviour as a function of the bias voltage.
