I had the same problem, I used a column with the volumes of the goods on my own ship, and I really missed it with this mod, so I decided to add it from base trade system.
I think this can be useful to other players, so the topic's author can update his mod. ;) I tried to transfer the code from the base tradeoverview.lua as accurately as possible.
This is exactly what I came to the comments section for. Thank you for putting that together!
To OP: I really like this mod. It's quite good, I was going to say the only thing missing is the "You" column that you could sort by what you have in your cargo hold, but the last poster already added that xD