i have fortuner legender and its uncomfortable too but u get used to it, if you get the ironman or ARB oldman emu shockabsorbers like i did for my 2017 Revo Hilux, it did made difference but very minimal like it got 10-15% comfort than original ride, later i got ARB oldman leafspring tht made the biggest difference at the back seats.
If you want to make it softer get those comfort shock absorbers like TRD, ARB Oldman emu or Ironman, most of them are happy by changing it but keep in mind Toyota Fortuner have ladder chasis so it will never be comfortable as other SUV like PRado, Landcruiser or even locally made crossover.