Unless you know something that Tess herself doesn't about her game, they are two different ninjas.
Plus in the boat meeting the Gambit Queen even says "I wasn't sure which one of you would come..." or something along those lines. So even if you don't catch the clothing and mask change, that's a hint that the Gambit Queen has been in contact with more than one sister.
It's assumed to be Alessa because Grym Gudinna is self-aware of her evilness, says that she's happy with her life, and commands a loyal Pat. Also, the Gambit Queen said that Alexander's humanity died before Grym Gudinna was born, meaning it could only really be Alessa or Jules since the other ninja was Veronica. I forget if Astrid was still in cryo or not but either way she wasn't walking up those temple steps. Jules scene with Gary showed she didn't know much about the Gambit, whereas Grym Gudinna seemed to be aware of more details.
Well then that was a terrible decision to have them look basically the same and not even change the color of the "????"... that's extremely confusing in an already super complicated game.
Also, on the boat she says she wasn't certain it would be her, but I thought she might've been expecting ninja chick who did also show up, she just remained unseen.
Couldn't it be Dominique tho? I'm not seeing why would Callista trust Alessandra... that's a bit weird. At least Dominique does good, even tho she struggles with her evilness (which would also fit with that particular line of dialogue) and she's working towards a similar-ish goal... Alessandra doesn't seem to be interested in anything except for maintining her status quo. Is there a theory or a common train of thought on why would Callista be so chummy with Alessandra?