From a set of 8 10243 simulations where the parameters are:

βHe=[0.30.9] βH=[0.61.0] ΔzHe=[0.00.8]

First I fit each redshift independently:

The 95% Highest Probability Interval from the posterior distribution of the fitted parameters ( as a function of redshift, since each redshift is fitted independently ) is shown below, there are no constrains for the Helium parameters:

Now I fit all the redshifts simultaneously:

And the posterior distribution of the parameters are:

Resulting in a delayed Helium reionization but with High photoheating and photoinization rates.