My opinion about the HQ-9 and HHQ-9 ranges is that.... they are --- like all AAMs and SAMs --- very much dependent on the RCS of the target, and that paper numbers are useless indeed.
The SAM missiles usualy moving on ballistic path, means 1000m/sec has 100 km, 2000 m/sec has 400 km range.
The RCS is not a problem on its own, if there is meter lenght radar thn the f35/b2 etc has quite big radar cross section on those wave lenghts.
The long wave radar can direct the X band targeting radars , even if the X can not see the target the missile can be in position/range to see it with the small radar receiver on it.
Or the missile can use infrared seeker or whatever that they can fit.