My point is that Gloriosa is an unreliable narrator. Her saying Tritoma "died" is without any other evidence besides her word, and the Kuja girls are all pretty naive to anything outside their borders.
Also the translation leaves some room for interpretation because 同じだった is following her direct words of Tritoma getting the illness
and dying, while the そう is indicating it "seemed like" Shakky went similarly. Hence why it reads like Gloriosa is actually not certain of what happened, just that both empresses got caught by cupid's bow at some point.
All I'm saying it, I wouldn't be shocked if Tritoma makes a reappearance in the story. Very unlikely, but not 0%.