Total Volume for each major muscle within a program
When the word "volume" is used in sport science research, it is referring to the number of total hard working sets per week (a hard working set is a set taken with 5 reps from failure). Yes this means that "high volume" means a lot of working sets, not a lot of reps.
In order to track and progress volume, it would be good to see the number of sets sets programmed on a per muscle group basis. At the moment, the only way to do this is to manually count sets.

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Coach George commented
I would have to disagree with you here as the Volume in literature is actually counted as:
No. of Sets x No. of Reps x Intensity (Load) x Distance Travelled (some have longer limbs, some have smaller limbs, some do half reps, some do full reps).
So, I think the actual Volume in Trainerize, which is Sets x Reps x Weight is a good option.