Okay so I'm not entirely sure if I understand what you're saying, mainly because I'm a bit stupid and usually need a while to fully understand things being said, and also all the Evoland 2 time travel stuff is confusing anyways
But my understanding is that final cutscene with Fina in the Laboratory up to Ceres portalling him is Giro, and then everything after, up to the Ceres boss battle is Kuro, yeah? And that Kuro's existence only comes about via the time loop (which would tie him in with Ceres, who shares that feature (maybe that could also explain why she can't erase him? Because he's tied to the Project via this like her?))
Though I'm pretty sure I understand some of the details wrong
Okay I can understand some of this logic. For one, it can explain how Sid confused Giro with Kuro in his backstory, because they were one and the same, and like I said, possibly explains Kuro and Ceres' intrinsic connection. And maybe also the Project being involved in the "creation" of Kuro could explain why he looks like a teenager when Giro probably wasn't, maybe he got "reset" back to how he was supposed to be when he first time travelled to the Past Era
Though I do question why Giro and Fina would have gotten together, because again, Sid exists. Was Giro just like "alright I guess you're my lab assistant" and did Fina either not recognize this wasn't Kuro, or convinced herself that helping Giro could bring back the Kuro she knew? I mean I can believe she went a bit crazy with the final few cutscenes, but I don't know
I'm also not sure why then Fina would have died/disappeared, if Giro didn't get rid of her. And also, I think in his first message he says he "disposed of the defective model, him and the woman" or something like that, something that implied there were two people, the "defective model" likely being Kuro
And also, there's something up with Giro and Ceres, but I can't quite put my finger on it. You're correct about the fact that the Molecular Research Center people never mention Ceres, and yet Giro knows of her, and seems to have specifically come to this era to deal with her. Is that what you mean when you're talking about how the Project would've changed Giro? Like sometime in between when he was first sent on his mission and when he first comes to the Laboratory, he learns about Ceres and makes it his mission to get rid of her, presumable through her tampering with the Project?
So then with that logic, the timeline we're first given to understand makes more sense; G was sent back to help with the Project, loses his memory and becomes Kuro, but then by the end of the game, his dealings with Ceres and the Project somehow bring back to him his original goal and he becomes Professor Giro when he meets back with Fina again?
I don't know, like I said, this is all so very confusing
But back to that bit about Giro and Ceres being strange, I want to point out that from what I understand, his intent was to destroy her, and when he couldn't, he made the Weapon as a way to weaken her, so the Weapon wasn't part of the original plan (which fittingly would make it an "Anomaly"). But also, I think in the final log (which I don't have saved) he says he plans on letting her out of the device and questioning her, which implies to me that he doesn't really understand what exactly Ceres' role in all of this is, and also that the Weapon, which Kuro is programmed to fire, was never part of the plan
It's not entirely relevant to your point, but it might have some relevance when it comes to Giro, and I have not fully fleshed out this information into a coherent thought either, so I just wanted to bring it up as potential info