I feel like Gallia should be above Ti, if this is canon. Possibly above Kolar as well, due to the lack of feats for either Ti or Kolar.
That said, the Grand Inquisitor loses to Adi Gallia. Gallia outperformed Season 1 Anakin against several BX Commando droids, and by a wide margin in the episode Grievous Intrigue. Anakin bested at least 2, or up to 4 BX Commando Droids, while Gallia defeated 6-8 (two die off screen, hence the uncertainty in the numbers). Anakin even seems to acknowledge her superior combat performance, when he chooses to stick with Eeth Koth and recommending Gallia pursue Grievous, rather than volunteering to go after Grievous himself.
So going by both her performance, and Season 1 Anakin's expressed views of her capabilities (believing she would be better equipped to handle Grievous than himself), Adi Gallia should be comfortably above anything the Grand Inquisitor can handle.
First, Luminara was never even on the Jedi Council.
Second, she is factually below Season 1 Asajj Ventress. The Grand Inquisitor has been directly compared to Asajj (presumably at her peak) by Dave Filoni, with Filoni implying that the Grand Inquisitor is barely below Ventress. This should put the Grand Inquisitor above Luminara.
Third, there's no reason to scale the Council members to Luminara, even if she had been on it. Being on the Jedi Council doesn't automatically mean that a Jedi is powerful. Look at Trebor Coleman or Jocasta Nu for some excellent examples.
It's been a long while since I read the Essential Guide, and I don't own a copy myself. Mind quoting the passage for me? Because from what I remember of the episode, Luminara basically outright admits that she shouldn't have tried to face Asajj alone.