A brief check:

• Concerning the mechanical resonances, the SR suspensions have the following modes at around the frequencies (from 5 to 50Hz), according to the model prediction (ref):
  • at 5 Hz, RM Pitch,
  • at 11 Hz, RM Vertical,
  • at 16 Hz, TM Roll
  • at 50Hz, RM Vertical.
• About 17Hz, it could be the RM roll mode coupling.
• about 30 to 35Hz band, it would not be due to a pure mechanical resonance since the suspension does not have resonances at the frequency band.