A colour negative, though diffused, may still confuse the test rig if the negative in question does not integrate to neutral grey.
Photos exposed outdoors, with sky, and land typically do integrate to neutral grey.
I would presume if all tones integrate to give neutral grey, then the r, g and b rows would have the same intensity for the same time. Any discreprancy must then lie in the response of the paper.
So from your results I interpret you need more magenta (anti green) and quite a bit more yellow (anti-blue).
For me, filtrations with Kodak paper and Kodak or Agfa negs typically are in the range of 50M, 80Y. Fuji Reala is a totally different filtration for me.
To get more red, expose longer.
This rig might just give you balance, but the times on its edge suggest to me that the trial exposure should be 60 seconds, kind of like the Kodak print exposure guide.
Then with the 60 seonds trial exposure, balance the colours, and then read the time for unduffused exposure off for the tone of density you like.