So I think I know what's going on here, and I'm leaning towards there is no bug.
I thought I had replicated this, but in looking at my video frame-by-frame (with game animation at 1x), and in particular looking at the turnmeters, I think I found the source of the illusion. Because the Sidious datacron prevents assists, using Inherited Teachings results in no character animation whatsoever. This results in turns happening faster than frames can be drawn. In my video, there was literally a single frame difference between three characters' turnmeters reducing, so it seemed all at once. Everything that was going on in my video seemed consistent with characters taking turns and using Inherited Teachings on each other. While a casual view makes it look like they are getting too many stacks of Jedi Lessons, an astute investigation of the frame-by-frame differences does not yield any evidence of a bug. The fact that the toast text is limited in how much it can display, and can sometimes display on turns other than the turn it was applied--just due to the timing of the presentation of it--means that interpretation of the toast text can be difficult as well, especially on fast speeds.
The original video posted here is harder to examine because of the 4x speed on auto and the low quality of youtube, but you can see some parts where Sidious appears to lap JKL and Yoda without their turnmeters moving at all. I don't think he is actually lapping them, but rather they are taking their turns and using Inherited Teachings on each other, but you can't see it because there is no corresponding animation, and the computer's next drawn frame is for someone else's turn.
I don't think there is a bug here, just that it seems very fast because the lack of assists means you are missing when characters are taking turns.