I only own a German copy of the book so it's difficult for me to provide good quotes but I will try to explain my view on this question nevertheless. I haven't found a passage that explicitly answers your question so I will try to give you good arguments.
Qordis told Bane that he knew about his secret training with Githany the morning after Bane defeated his star pupil Sirak. I'd say it's save to say that Qordis, being a Sith Lord, had the means to find this out by himself long before the fight (and as head of the Sith academy he would have wanted to know what was going on and what the students did). He talked with Bane about it in his own room when no one else was around so he had no reason to lie to Bane in order to convince others that he was behind Bane's success. (Nevertheless he could have lied to Bane in order to let Bane think that he (Quordis) had everything under control and wasn't suprised by Bane.)
Furthermore Qordis was arrogant enough to know about Bane's training and just ignore it since he deemed Bane worthless and thought him already completely defeated - a thought Qordis might have been more than willing to accept since this meant also a disgrace to his once arch-enemy Lord Kopecz who brought Bane to the academy. Maybe he also wanted to see what Githany was planning (and plotting against other students was encouraged at the Sith academy). She was a much more promising student and those students were given more freedom in developing schemes against others.
I know it's not a definitive answer but I hope my reasoning convinced you that it's likely Qordis really knew about Bane's training with Githany but he ignored it until it was too late.